Grubbe GT5 from the case up ....

Davezilla said:
Nice.. you got a really good deal on that cranbrook and converting it to a trike will be cool and a lot of fun too. those type trikes don't like quick turns tho and can tip over, but it's also fun to ride with one of the rear wheels off the ground. You might want to consider lowering the rear section and using a layback seat post to put the rider weight further back for more stability... and a lowered cranbrook trike would really look cool
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Then its settled !

A lot more on the motor on monday when i get back including porting the case to the jug and making the port map ¡!
 
ok i am back and got some work and math anf therories figured out !

i decided i am only going to buy what is nessasary and not go crazy on this thing LOL i am building a hybrid super stock mod motor !

the bottom end will be the stuffed gt5 case with flowed transfer ports port matched to the jug and a 38mm stroke 1 piece crank balanced and stuffed crank pin and holes, on a ZAF-60 connecting rod and running a type B piston low wrist pin hole.

the top end will be from a 40mm stroke dax f80, i am running a slightly used f80 take off jug that has been transfer port matched to the case and cleaned up and ported for max torque and high rpms... a wide and downward D shapped intake with a rounded off roof and a verry wide exaust port that is only slightly raised and rounded out.... the jug will have to be decked down for proper squish and deck hight because the new 38mm stroke crank and type B piston leaves the piston a tad low in the jug compared to the 40mm stroke crank and type A piston

the head is a brand new take off from a dax F80, it has the thick gasket surface and a small combustion chamber with no squish band. just a small tight hemi dome, the decked aria will be a horizontal squish when i am done. around 12:1 comp or a 6cc dome

the only actual performance parts i am going to buy are as follows.....

1 titainium wrist pin and bronze bushing, i am going this way because the setup is 2 grams lighter than stock and i will never have to worry about high rpm needle bearing failure !
2 a cut on gt5 piston... why ? well its only 10$ more than a stock one and i dont have to do t myself LOL the cut on piston will have a trimmed skirt also and have some holes drilled for lightning the whole top end should be 3 plus grams lighter than stock
3 a 16mm carb dellorto 16.16 or mikuni vm16
4 i might buy a power plenum intake from fred if i cant properly port match the large bore steel one good enough, if i get this it will be bolted to the jug and port matched perfectly to the jug.
5 skf case bearings and seals and copper gasket kit from juice moto parts.
6 a nkg b6hix iridium plug

some time in the future i may order the new diamond head thats out and bolt it up for a good squish band head with nice heat dispersion

other than some gaskets that are custom made and a light wrist pin and bronze bushing and some upgraded bearings to sustain high rpms, the motor will be almost compleatly stock appearing !

i will have a heavily modded super stock race motor !


i made a video and am uploading it now of the set up i have planned and some new port work and the transfer port work i did to the case and jug

i will post it in a few so let me know what you think !
 
ok here is the video of the hybrid motor ....

stuffed 38mm crank and ZAF-60 rod with a type B piston and a 40mm stroke motor jug and head..

i have to finnissh porting the jug and decking it down and pick up the juice moto parts rebuild kit and a cut on type B piston, then i can put the whole case together with copper gaskets and and titainium pin and bronze bushing on the rod and have the whole bottom end done and ready to go

then all i have to do is finnish the jug and head and buy the carb and exhaust..

i will be ordering the juicemotoparts kit tonight ! it comes with skf bearings and seals, wrist pin and bushing, copper head and base gaskets and copper coated other gaskets.

anyway here is a video i will see what i can do about pics.....

https://www.youtube.com/watch?v=QgyUKNgfOxQ

tell me what u think of the transfer port work and my port job
 
So i got the bottom end together and man what a pain in the ass that was! i mean just assembling it is easy but getting the 2 case halfs aligned so the bearing bosses are perfectly linned up to the crank is a real problem. I had to get it all together and feel out the play and add shims to each side and after a few tries i came out with 3 shims on each side to get all the play oit . Then i had to tighten it down and spin it by hand and feel the resistance then loosen it up and tap the case half and retighten it up and feel it out again . I had to do this a hundred freeking times to feel out the right spot with the least resistance where the crank is best aligned with the cases. It was worth the extra effort thou as now the crank os true and near perfectly alogned woth the case! it spins verry easy and freely it spins with only a single finger and hardly any resistance with no side play with the case bolts torqued down all the way! !!!!!

Anyway i am uploading a new video of the finnoshed case for you all to watch soon give it an hour or so.

The only thing i have to do now is go through all my stock take off and spare parts and select the best magneto with the most retard then select the best coil woth the best continuity then assemble the clutch and find a set of better clutch pads and tap out and insert a grease fitting into the case where the cluch adjuster nut was then fabricate a arm for a new adjuster nut.

Lol all that and a can of paint and we should be in buisness lol lol
 
here is a new video of the stuffed case build

https://www.youtube.com/watch?v=IVnN1kBaxWk

i find videos to be more usefull than pics and its easyer to explain what you need to by vid vs pic....

anyway...

i figured out why the magneto wheels are all over the place ..... they are really not all over the place with the timing, what the differance is from motor to mnotor is the timing differance between the 40mm stroke and the 38mm stroke motors and there various con rod combos and piston wrist pin hights, so if you have a 38mm stroke and a ZAF-60 rod with the high pin , the magneto wll be keyed differant than the 38mm stroke with the ZAF 50 rod and low pin ... it acounts for the differance in port timeing via piston pin hight... also the 40mm stroke will be differant than the 38mm stroke and so on and so on .... this acounts for all the differant magneto timing changes from motor to motor.

thought i would post that because i saw quite a lot of people ask why the mag wheels were so differant even through out the same size 66cc motors and the 40cc motors, and from what i have learned its because of all the differant stroke, wrist pin, and con rod combos....
i am willing to bet that if you had 2 mag wheels from 2 motors that are the same stroke with the same rods and piston pin hights they would be right on with each other to within the normal tolerances for this type of motor

enjoy the video !

for the coils themselves.. well they should all be the same between all the 66cc and 70cc motors and all one has to do is choose the one with the best continuity and soldered joints


ohh and i plan to add a secondary coil behind the main so i can have a dedicated coild for lighting and not have to draw energyy from my main coil and spark !
 
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here is an updated video of the build !

i have the proper magneto that has the correct timing advance and key slot for my crank, rod, and piston combo... it should fire just before TDC like 40-30 deg before or something around there

also i have installed the cclutch shaft and clutch shaft bearings, the bearings for the shaft i installed with the interior dust shields removed and i packed them with new bearing greasee and then packed the shaft itself with grease and i am going to run a grease fittting instead of the adjuster nut this way i can regrease the bearings and shaft with the squeeze of a trigger

i have one question though... does the clutch pack bearing require grease or are they run dry ? i am talking about the bearings in the clutch disk itself ? does it run dry ? or does it come appart to grease the bearings ?

https://www.youtube.com/watch?v=FTBeV5DHRsA

you can see what i mean in the video...
 
Ok the clutch is finnished and the worm gear teeth have a light coat of bearing grease on them, i went with a set of stock clutch shoes cause well i couldnt find anything else that would work better or any type of ugraded shoe so i went wit a set of stock ones i had around.

I have all the side covers and cover gaskets on and the entire botom end is ready to roll!
I even made a new seal for the hole the wires come out of a rubber stopper with a hole drilled in it and the wires fed out the hole and then i gorrila glued the hole and wires in place so it can not be pulled out and its waterproof! !!

All i have to do now is do a light rough up on the case and covers with emerycloth or scotch bright and hit it with paint.

On to the top end tomorrow . . . I will be ordering a cut on piston and a titainuim wrist pin and broze bushing , i know i said all stock parts but i realy do not want to build a high comp high performance motor and destroy it with a failed needle bearing hours later lol

I will finninsh decking the head down to 5.8 to 6cc's to get the comp i want. I will use a flat lexan sheet and a syringe to measure the head volume till i get it right.

Then when my piston comes in i can set it up without the rings and start doing squish clearance tests and decking the jug down til i get a tight and effective squish band and i should be ready for final assembly! !!!!!
 
I will tell you guys this . . . This is the smothest turning and cleanest rotating bottom end i have ever seen on a china girl ever by far! !!!!!

I can place a single finger on the con rod and with just that finger rotate the whole assebly all the way to the sprocket with the clutch engaged and it moves almost effortless
 
the video says you're running a 38mm stroke bottom end with a 40mm top end... what exactly does that mean? Your stroke will only ever be as much as the crank gives it...
 
mew905 said:
the video says you're running a 38mm stroke bottom end with a 40mm top end... what exactly does that mean? Your stroke will only ever be as much as the crank gives it...
Click to expand...

i suck at discriptions and explanations lol

well it means ... i am running a grubee gt5 case with a one piece 38mm stroke crank and a ZAF-60 rod from a 38mm stroke grubee gt5 and a grubee gt5 type B piston with the high wrist pin hole, .... the top end IE: the jug and head ..... are from a dax F 80 witch has a 40mm stroke and a differant mm con rod and low wrist pin piston,

now what i am doing is matching the head and the jug and its port map from the 40 mm stroke motor to the 38mm stroke bottom end .... to do this i need to space the jug up with a custom 1.5mm base gasket and then deck the toop of the jug off to get the propper piston deck hight and squeltch clearance.

with a 40mm stroke top end on a 38mm stroke bottom end running a 1.5mm base gasket at bottom dead center the transfers are open a noticable bit more than with the stock top end and the exhaust port lines up with the pistons crown mutch better at BDC also ! the problem one runs into with this setup is the jug is too tall for the 38mm stroke motor and it causes the piston to sit to low in the jug therby causing lowered compression and rendering any squish band head you use ineffective, to fix this you need to deck a considerable amount of the top of the jugto bring the piston to the top of the cilynder and to get the right squish hight.

but it can be done relitivly easy

just dont try to runn a 38mm jug on a 40mm bottom end lol ! not without considerable work IE: swapping rod lengths and piston types and custom jug spacers. it would be easyer to retro fit a puch jug and head !!!!!!
 
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rogergendron1 said:
i suck at discriptions and explanations lol

well it means ... i am running a grubee gt5 case with a one piece 38mm stroke crank and a ZAF-60 rod from a 38mm stroke grubee gt5 and a grubee gt5 type B piston with the high wrist pin hole, .... the top end IE: the jug and head ..... are from a dax F 80 witch has a 40mm stroke and a differant mm con rod and low wrist pin piston,

now what i am doing is matching the head and the jug and its port map from the 40 mm stroke motor to the 38mm stroke bottom end .... to do this i need to space the jug up with a custom 1.5mm base gasket and then deck the toop of the jug off to get the propper piston deck hight and squeltch clearance.

with a 40mm stroke top end on a 38mm stroke bottom end running a 1.5mm base gasket at bottom dead center the transfers are open a noticable bit more than with the stock top end and the exhaust port lines up with the pistons crown mutch better at BDC also ! the problem one runs into with this setup is the jug is too tall for the 38mm stroke motor and it causes the piston to sit to low in the jug therby causing lowered compression and rendering any squish band head you use ineffective, to fix this you need to deck a considerable amount of the top of the jugto bring the piston to the top of the cilynder and to get the right squish hight.

but it can be done relitivly easy
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Aahhh. Okay, You measured the crank though? because to my knowledge the only difference between the F80 and the Grubee is the rod length. The shorter rod will help your low end power, but they're both 38mm stroke. The GT5 with the low wrist pin has an 80mm rod, the F80 has an 85mm rod, setting the wrist pin 5mm higher for a more neutral balance. The ports are also slightly different. The only motors with 40mm strokes are the super-rats, and the Arrow 11hp race engines (stroked to 42mm actually if memory serves). Even the GT5a was told to have a 40mm stroke, but both my bikes run the 5a and they both have a 38mm stroke. If you want, I can even post my measurements of the crank from the 5A for comparison. Sorry to shoot down your build, hybrids are still a cool idea.





crank center to big end rod center comes out to 18.77mm, which comes out to a 37.54mm stroke (38mm). That's a Speed Demon 80cc crank (same ones Dax F80's are). The rod is 80mm eye to eye (110mm) for the low wrist pin, 85mm eye to eye (115mm) for the high wrist pin. Only difference between that and the 5A is the rod in the GT5a is 80mm eye to eye (low wrist)
 
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Awsome! !!

Thank u for clarifying this info?!

I was under the impression the gen v and dax f 80 were 40mm stroke cranks and thats how they got the 69cc vs 66cc rating dax is 40mm stroke and 47mm bore vs grubee gt5 38mm stroke and 47mm bore

i know this , that dax jug is taller and the port map is a bit differant . I need to run a 1.5 mm base gaket to line tha ports up correctly at bdc and deck a whole lot off the top like close to 1/8 or. 1250 to get anywhere near a good deck hight .

And thank you for those pics! i save all tech drawings as i and taking classes for auto cad and masterr cam and geometric dimentioning and tolerances

I was under the impression the dax was 40mm stroke cause thats what it says on the website ie: 40mm x 47mm though i never pulled one appart and actually measured the crank stroke so i am not shure
 
It could be 40mm stroke, but I've never heard of one other than the superrat and the Arrow stroked cranks. Only way to find out is to actually measure (you can measure center of crank to center of big rod end hole, or measure distance travelled in the cylinder. I know one of the cylinders has the ports only a mm or two higher than the other, which one I can't quite remember but I remember having issues with it. I'm pretty sure it was the Speed Demon/Dax jugs that were a couple mm too low, as the GT5a I got just two weeks ago has plenty of breathing room.
 
I am surprised that nobody has chimed in with the answer to greasing the clutch hub bearings. The answer is yes, they are lightly greased. White lithium grease is recommended.
Only use a very small amount to help prevent fling out which will contaminate the friction pucks.
Looking on the back side of the hub assembly there should be 3 tiny through holes that are drilled into the bearing race. You can carefully pack grease into them using a tooth pick and rotate the ring gear on the hub to spread the grease all around.
 
The jug i have is a new take off from a dax f 80 i am running on a differant bike . So i can not measure the crank stroke as the motor is in use on my race bike lol it was to my understanding that the dax and motorbicycleracings gen v were the same and had a 40mm stroke by 47mm bore bringing it to 69cc and all the other motors were 38mm stroke by 47mm bore but now i am not shure lol it did say 40mm stroke on the website though?

Anyway the ports are a bit higher up on this jug everything is hogher up, and wit a thicker gasket the piston crown sits near perfectly level with the transfer port floor and exhaust floor vs covering it up halfway on the transfer and coming 2-3 mm over the exhaust on the stock jug!

thats why i am going through the trouble of useing and modding this , to have a jug where the transfers are fully open to the crown of the piston and an exhaust thats fully open to the crown of the piston eliminating a lot of turbulance.

In one of the videos you can see how close they are to perfectly open with a stock base gasket and how they only need a hlaf mm more to match up , but in doing so i will meed to remove a lot off the top of the jig and thats why i did not touch the roof of the exhaust sode from cleaning it up , i want a good amount of blowdown and dynamic compression and not loose charge through an abnormaly high exhaust port roof
 
See the exhaust is already higher than the stock jug a lil bit that and i am raising the jug a half mm and coupled with me decking aboit 1/8th off the top of the jug . . . The exhaust port roof is now as close to the top of the jig as i would dare put it in fear of too mutch lost charge and compression and suffering low end so i left the exhaist roof alone. I will try and get some deg measuremenyts soon on the port map
 
I guess to gain back some low end i could run a stock base gasket and not deck the jug as far and that would give me more distance from the exhaust port roof and the top of the jig and more distance there means more power and usable dynamic compression but less top end .

Ahh idk lol what are your thought as of right now the exhaust port roof is stock hight but cleaned up well and the exhaust port is been widened pretty far
 
ok i ordered the cut on gt5 piston and rings, when it comes in i will trim the skirt and then mount it and set the jug deck hight.

on fri i will order the titainium wrist pin and bronze bushing

once the jug has a good deck hight i will begin the top end assembly !!!

i am verry woried about over heating though with high comp on a stock head ..... i may order the diamond head from JNM or the fred head in a 5.8 to 6cc chamber and runn that with a copper head gasket.

for an exhaust i am going to run the JNM fatty pipe AKA the snake pipe with a 1in inlet diamiter
 
On another note i confermed at the dax website that the dax f80 is a 40mm stroke 1 pc crank with a 110mm con rod and the top end from the dax motor i built is what i am running on this build

also i got some other work done on my dax f80 racer! i cut up and fabbed up a new longer and better flowing strait pipe and now i just need my fiance to weld it up for me lol she is a certified welder and welds for a living! the old strait pipe on my dax racer was basicly a stock exhaust headder cut off before the muffler chamber and a megaphone welded on it lol it was only 16in long and man is it loud but wow the top end it produced and how easily it flowed could not be beat! i had to up jet to a 74 main!
The new one will be port matched and made of 3/4 in steel tubing with smooth bends and it will go over the motor and down the frame to over the rear tire . The length will be a lot closer to a tunned strait pipe length for street riding , it will be 4ft 6in long in tottal so the bike should gain back some midrange wile maintaining a super high reving powerfull top end.

And i got a set of 1.6in wide rims for it with new hubs too the rear is a shimanno coaster hub cb 110 with a 22t sprocket . I got the front all set up and man it barley fits inbetween the fron forks with the new wide rim and fat tire! i am waiting on installing the rear tire for when my rear hub adapter and 40t sprocket come in
 
I am going to take my time with this build since i am working on my regular street racer at the same time doing a fat tire conversion and regearing , i am short on money now and i need to get a sprocket adapter, a 40or38t rear, and weld my fabbed up exhaust, and make a lay back seat post all just for the street bike i am riding now!

Thats going to be priority but inbetween and when money is available i plan on ordering . . .
The titainium wrist pin
the bronze bushing or wider high quality moped bearing
the JNM diamond head or fred head . . . I am in fear of the stock one over heating at 12:1 comp
the JNM fatty pipe
and i need to decide on an intake . .arrow reeds or power plenum?
And lastly a good carb . . . Dellorto phgb 18-19 or mikuni vm 16-18 or dellorto sha 16.16
After that a iridium plug and mabe the HD lightning ignition but as far as i can tell from my personal experiance and from what i have seen on most all the race bikes the stock ignition seems to work well but may be iffy under higher compression
 
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