Grubbe GT5 from the case up ....

[rogergendron1]

Uthanks for all the help and a piston port trail bike is exactly what i am going for with as mutch midrange and upper mid as possable but still have a compramize on low end power

you should have seen the burnouts the jug with the 24mm exhaust ports could do lol it was a verry high rpm bike and only made power past 6.000 but once you were up there there was no stopping it from cranking that tire fast as **** lol i ran a 44 t rear to compensate and gain back tourqe through gearing taller and man i smoked the knobs off a cheap k mart mountain bike tire on pavment in a mear few seconds lol

the ports on that jug were just an experiment to see how far i could take the intake and exhaust and still have the motor run lol

the exhaust was so tall i actually cut through the roof and had to jb weld it closed lol and the intake was real low and wide and i toool 4mm off the entire intake side skirt of the piston! it was probably the most intake duration one could wver run on a piston port mptor . . . I mean it did not idle at al if i stopped so did the motor unless i kept reving it to keep ot running and there was no low end at all and the midrange went down too but . . . . The top end . . . . Good god! !! It was unstaopable in a narrpw but super powered high rpm range 6,000 to 9,000 is where it pulled hard . I mean if i was in that rpm range o could take any hill even crazy 30deg dirt hills withot it flinching cause of the 44rear and 26 tire but i couldnt get out of my own way under those rpms or even take off from a dead stop thats how garbage the low end was

 

[rogergendron1]

I supose if i had a shift kit and a 7speed nexus on a 24in wheel it would have been a mean bike to race on the trails! !!

 

[GearNut]

Hmmmm.... Rig up a power valve for it?
Have your low end and crazy high end too!

 

[66sub]

i have some great ideas on ex port shape there is lots to play with but u should shoot for less width

 

[rogergendron1]

Ok plans are all jacked up now and i am ripping mad! !!!!!!

I went up to my dads machine shop and picked up the piston on the way . . .

Got sent the wrong piston! it said gt5 motor right on the invoice but i got sent a low wrist pin piston i cant use at least in this motor i am building now so i am at a standstill again

and when i got to the shop i went out back and saw a familliar box sitting outside on the grass so i opened it up and almost cried . . . The box had my gx160 race motor bottom end in it! !! And it was sitting outside for months! !!!

Good god its ruined! !! I just had the bore honed and put in a billot con rod and a forged piston and a mild midrange cam and removed the govener and oil sensor! i had hours of work into that to get a zero deck hight and hundreds of dollars of work and parts into it including a billit steel flywheel witch is rusted solod now! !! The whole gx160 is rusted solod as a rock! !!

Aaaahhhhhhjhhhh


aaaaaaaaahhhhhhjhh


huuuuhhh aaahhhhhhhhhhhhhhhhhhhh!!!!!!!!!!!!!!!!!!!


It was all done the whole bottom end was done all i had to do was finnish the high comp head and slap it together but now its done ruined! !! All that work . . . Even the box of gx160 and gx 200 carbs was full of water and 7 carbs are ruined . .

I dont blame my dad though he is handicap and on oxy so he probably moved it and hurt himself then left it and forgot , aww man what a shame . . . Awwww man aaaawww man , . . .

 

[rogergendron1]

Awww man i still can believe it

Gx160 with an over bore and freshhone with a forged wizeco poston and arc con rod set for a zero deck hightand running a billit steel flywheel from nr racing. . . A box of 7 gx 160 and gx200 carbs all ether jetted or bored all ruined. . .

The motor is litteraly rusted solod as a rock . . . .

That motor before i pulled the head to do the swap to the high comp head sent a 300lb go kart down a flat at 50 miles an hour running just over 10:1 comp with the flat top piston and rod in it and a stock new style head with just a minor port and polish and a set of 21lb valve springs

i was going to fully do up the 14cc head with a big bore vavle job and bronze guides and dual springs and swap the cam and run roller rockers the bottom was all set up for it all i had to do was finnish the head i got . . . All well life sucks then u die

 

[rogergendron1]

On the up side i have 3 gx 160 heads for grabs now lol

an 14 cc old style
and 2 18cc new styles

 

[rogergendron1]

Mabey i will keeep the 14cc old style and buy a new preddy 212 lol start all over

 

[rogergendron1]

all right enough of that lol

i am gonna stick that piston and the new set of rings right into my dax bike tomorrow as it probably needs em by now its got about 1500 miles on it and i will probably cut the tranfer ramps a lil more and add a small exhaust ramp too..

then i have to order a stock gt5 type b high wrist pin piston i think custommotoredbikes has the type b but i am not shure.

here is a video of the wrong piston and a good look at the 3 gx160 heads if you guys know anyone who might want a 18cc or 14cc head, they need new valve guids and the seats cut with a 3 angle job and a good port and polish then just clean up the outside and piant em ....

https://www.youtube.com/watch?v=Yy9Fl-gljRM


there ya go

also the 2 stroke carb i got is a 28mm kein carb way way too big for my aplication...

also have stock 21mm carb from a honda atc 200 and 2 27mm carbs with acselerator pumps and 7 gc160 and 200 carbs that are now only good for parts lol

 

[mew905]

Hate to say it but the GT5 piston IS the low wrist pin piston. You'd want the Type A or type D pistons (flying horse, PK80, etc.) to have the wrist pin higher up.

 

[rogergendron1]

wait i have the gt5 38mm stroke bottom end and the zaf 60 rod with the high wrist pin it sits perfect in the jug but the low wrist pin is out the top by 3-4 mm its in the video in one of the posts ,,,,,

anyway i need a high wrist pin piston to finninsh this

the piston that came out of it was a high wrist pin piston and it was a grubee gt5

 

[mew905]

wait i have the gt5 38mm stroke bottom end and the zaf 60 rod with the high wrist pin it sits perfect in the jug but the low wrist pin is out the top by 3-4 mm its in the video in one of the posts ,,,,,

anyway i need a high wrist pin piston to finninsh this

the piston that came out of it was a high wrist pin piston and it was a grubee gt5

That's odd... I've had GT5's, GT5a's and GT2a's and never, ever seen any with a high wrist pin. You should be looking for a PK80 piston, though. 21mm from crown to pin center (high pin)

 

[rogergendron1]

That's odd... I've had GT5's, GT5a's and GT2a's and never, ever seen any with a high wrist pin. You should be looking for a PK80 piston, though. 21mm from crown to pin center (high pin)

Wierd man lol you see the vid? that high wrist pin piston with the huge ramps and high cut skirt came from a grubee gt5 with a 38mm stroke and the zaf 60 rod now from what i understand there are two rods grubee ised for the gt5 the zaf 50 and zaf 60 i think i got the odd zaf 60 with the high pin eather that or i confused the **** out of myself and jumbled all the parts i have up but i was shure about muself cause when i strip a motor i put everything in labled zip lock bags and store all the parts together in a single box thats labled . . . Now i do have 4 tore down ht motors in my shop so . . . Lol i may have moved a crank and put it back in the wron box but i dont think so

i chose that crank cause it was the beat looking and the smoothest running crank with the least vibes i have ever felt in a china girl and the piston that was on it was a high pin but it came from my grubee gt5 box and matched perfectly to the case, the bearings came from 2 differant motors as i had to pull the crank bearing off of 2 old gen v motors to gwt japan bearings for all four bearing bosses the top end was a take of from a dax that wasnt even broke in ywt

i am 99% shure that the crank with the long 115mm rod and the high pin came right out of a gt5

 

[rogergendron1]

Idk man lol but whatever it is now and where ever the parts came from . . . All i can say is it turns over soo smooth and easy and being that its my best crank yet . . I fully expect this motor to rip off the line and rev to at least 9,000 rpms !

Best of 5 cranks the longest and best rod and a lighter high pin piston allong with a decked jug ported just right and a high comp head now thats a base for a strong motor

 

[rogergendron1]

Yeh eyebrow jug came off it but a strait shot transfer going on . . .

Well i am going on my army 2 week anual training starting the 12th so i am really at a stand still here . . . At keast untill i get back but i learned that crmachine man aka fred lives just an hour away from me so i am going to give him a call and mabey do an all day ride on my dax down there with my stuffed case and all my parts in a back pack and have a good chat with him right at his shop if i can set that up when i get back from training

i would love to go see fred in person seeing as he is only an hour away and talk shop and mabey come back with some new ideas for this stuffed grubee gt5 and i know he has the piston i need so its a double whammy!

Who knows i may come back with one of his heads in 6cc and one of his intakes on a 3rd tranfer port jug and a larger carb . . . I have a few bucks to spend now lol unkle sam is pretty good to me! !!!

His web page said he has the gt5 modded piston in stock with the high wrist pin so i would love to pick that up and talk to him about jugs and his heads and what he recomends for a good stuffed grubee gt 5

 

[Davezilla]

That would be really cool to live that close to Fred and be able to stop by and swap notes some, I know he sometimes has some one off goodies when he experiments with stuff so you might get really lucky there too.
I'm running his 6cc head and got a few sets of the brass exhaust stud nuts form him a while back and everything he makes is top notch. The reason I like the brass exhaust nuts is two fold, first is that they are about 8mm wide so lots of threads to grip and drastically reduce the chance of stripping out the stud or the nut, and second, the brass is strong but still soft enough to easily drill safety wire holes thru... oh... and they look cool installed too, I guess that makes 3 reasons to use them... lol

 

[Theon]

Don't think I've seen brass exhaust nuts on any thing since my Mini's, 20 odd years ago.
A great Idea though.