what did you do to your motorized bicycle today?

[mapbike]

I got the "Half Breed" engine together and on the old Western Flyer bike, got to pull the jug back off though, got it running and found I have an air leak between jug and case, the solid copper gasket I used will be coming off and one of the gaskets I make up myself and normally always use will go on it since the mating surface isn't good enough for the thin copper gasket to seal up.

Not a big deal but I hate to pull thetop off after just getting it all buttoned down nice.

As soon as I get this one clicking good then I'll get started on the GT5 build that will most likely go on the old Black mountain bike and I will retire the old Red Bat BGF engine that although it runs good it will vibrate your fingernail off about 28mph, always been that way, crank is so out of whack it ain't even funny.

I'll just clean it up and set it on the shelf, it was my first HT engine back in 2009, it has lots of miles on it but I recently put a new piston and upper bearing in it, all that will come out and go into another engine at some point since it has less than 20 miles on it, I have an extra odd ball almost flat top piston like the one that came in this engine that I'll stick in it with a new kit type upper bearing, then buckle it all back up and stick it on the shelf as a conversation piece in the shop.

Had a great time working on the new engine and the old bike today in this mid 60's temps we're having this weekend, cold at night but about 65 mid day... real nice weather for tinkering outside.

 

[Davezilla]

Good to hear you got that one running... too bad about the case leak tho...
I had to mill off nearly .040" from the bottom of my jug too just to get it flat and true so it's either chuck it in a lathe and clean it up, or paper gaskets down there...

I was too busy to even start mine today, had to change out a set of hub bearings on an 06 Sentra as well as doing a LOT of inspections so the bike just sat lonely today...

 

[mapbike]

Good to hear you got that one running... too bad about the case leak tho...
I had to mill off nearly .040" from the bottom of my jug too just to get it flat and true so it's either chuck it in a lathe and clean it up, or paper gaskets down there...

I was too busy to even start mine today, had to change out a set of hub bearings on an 06 Sentra as well as doing a LOT of inspections so the bike just sat lonely today...

Yeah the bottom of the jug is probably untrue and the case may not be as good as it needs to be either, it looks like it mates up nice and tight, but that thin copper gasket just aint gonna seal if it isn't dang near perfectly flat.

I'll just put some of that real stringy aviation gasket sealer on one of my home brewed gaskets and buckle her back down and that should be problem solved.

this thing sure acts like its gonna be a smooth low vibe engine, but until I can get it running right and get a few miles on it i wont know for sure what I have.

 

[scratchbuilder]

Greetings...hey its nice to look forward to the mailman..got some parts for my jackshaft mounted clutch. Wondering if the gearing will be easy takeoffs w/ 20-25 mph.. Any help appre. Motor 11 to js11 to clu.11(35chain) to 60 freewheel w/22 back to a 7speed 36 tooth...whatcha think..

 

[Trey]

Rode it, had hella fun! Heat wave here- 35 and no wind. Sketchy ice though.
MUST build a winter bike.

 

[Davezilla]

Greetings...hey its nice to look forward to the mailman..got some parts for my jackshaft mounted clutch. Wondering if the gearing will be easy takeoffs w/ 20-25 mph.. Any help appre. Motor 11 to js11 to clu.11(35chain) to 60 freewheel w/22 back to a 7speed 36 tooth...whatcha think..

You should be able to cruise at around 25 mph pretty easily with that setup... what engine are you using so we can have all the info we need? A 66cc China Doll should hit those speeds easily with better acceleration from the lower gearing. What's throwing me off is the china dolls have a 10 tooth output sprocket so i gotta ask if your using a different engine.

 

[Greg58]

Hey mapbike it sounds like you have a lot of crankcase pressure like we talked about.

 

[mapbike]

Hey mapbike it sounds like you have a lot of crankcase pressure like we talked about.

LOL... Yeah problem is that a lot of the pressure is going the wrong way.....

I 'm fixing to gather myself in a little while an go pull that jug and replace that gasket, I'd like to take it on it's maiden road trip today for some low speed break in time.

It seems that this engine is gonna be a good smooth runner, but until I get it running right and get out on the road I wont know what I have for sure, and of course the longer it runs it will smooth up a little more, @ about 50-75 miles all my engine were settled in to how they were gonna run as far as vibes were concerned, never notice any improvements after that, an untrue crank or a badly bablanced crank does improve with miles added, once the gear mesh good and smooth as can be and the rings get seated to give the best compression seal, the rest will just be what it is and either you have a well balanced engine or you don't, more miles wont change that, so I'll know fairly quickly what this engine will do, after about 30-40 miles I run them the way I plan to run them, I have never used a long 100-200 mile break-in period since I dont think there is anything to be gained or lost by doing that, if the internals of the engine are good and things are right, it will break in quickly and all the miles of easy riding aren't needed in my opinion, so I'll keep things tight and do a couple plug checks and run the shoes off of this one very soon is my plan Greg.

PS by the way, I got that Blutooth device paired up, you were right just needed to press and hold one button long enough for it to go into pairing mode.

 

[mapbike]

well, got the air leak fixed on latest build and took it for a 7 miles round trip maiden run, running good.

was running smoother and stronger by the time I returned from the ride, I cruised most of the way @ 27-30mph.

I did open it up for just about 40-50yds and hit 39mph, then I slowed it down and never got over 30-31mph the rest of the ride.

I'm not seeing the near perfect" balance factor" with it so far but it's fairly nice running at 30mph

On the first start and run all of my dax lowers were smoother than this engine is so far, its better than my bgf engines but time will tell what it will be after about 50 or so more miles on it.

I really thinking these Half Breed engines need about .020-.025" milled off the jug to get the compression to where it needs to be.

It seems that the dax engines are not what they were, looks like they are GT5 engines now, a member just got one and told me after the jug was pulled he noticed first off that it has the high pin type B piston and jugven Duane says on his site it's a 38mm stroke engine.

This is disapointing to me if this is true since I like the Gen IV well balanced PK-80 engine lowers I've got from him, anyone know what the reason is for the change?

 

[mapbike]

put another 15 miles on the "Half Breed" running a little better business no where near what I expected from what I was told to expect from it, but we all know these engines are a rap shoot and you may get one thats a good solid runner and another one just like it that is an under performer.

it smooths out nice at higher rpm at at 39-40 mph bus it wont run that speed on the flat, it steggles to reach 35 on the flat so far, and the vibes between 30-37 mph are fairly harsh, way more than anyone of the dax Gen IV lowers I've run.

I think the biggest issue with this engine is low compression as far as power is concerned.

(Edited) Without milling .060" (.025" as I said before is not enough to get piston and deck height matched up correctly) off the jug and correcting the port timing issues there just wont be much performance to get from these engines compared to the 40mm stroke engines that have a good balanced and true crank and better port timing.

Because of the lower compression, these engines may have good reliability since the lowerend is under less stress and being 38mm stroke also helps take some pressure off the upper and lower rod bearing.

I think raising the compression on this engine and going from a 30T up to maybe a 34 or 36T might help this shorter stroke engine since it just doesn't have quite as much grunt as the 40mm stroke engine.

Seems at least the one I have is balanced well for high rpms, its butter smooth to about 28mph but doesnt get that smooth again until around 39mph and up to the max I registered at 41mph, I think higher compression and a lower gear ratio would get this engine into its sweet spot and help it to get there much quicker.

But all said and done , I got to enjoy 22 miles of riding in the 60 degree weather today after watching the Seahawks get lucky and beat the Packers, I dont think they'll be so lucky when they play the Patriots though.....


Had a good ride and watched a nail biter football game the wife and I have our health we are truly blessed so yeah.... it's been a good day and I'll get this "Half Breed" running better, I just wanted to see what it would do with nothing removed from the jug and only some port cleaning with no piston mods.

 

[joey1320]

I made some decals for the frame and number plates. i also found a plate at Home Depot which I believe I'll be able to use for my new fuel tank. I'll be using a 1960's vw beetle washer fluid reservoir as a tank

 

[GoreWound]

I drove it for the first time!
then it died.

 

[Davezilla]

That first ride is always the coolest... What happened tho? why did it die?

For me, today I took mine up the street to my favorite taco resturaunt for breakfast, but didn't turn on the gps to record the top speed... just rode it to enjoy it.
Then I had a few free minutes at the shop so I took the front wheel off the new bike to chean up the bearings and re grease them, found a bit of roughness in the front bearing so I took it all the way apart and cleaned everything to see if it needed new balls or if the races needed replacement, luckily it's just a nick in one of the outer races and I got a few spares...

 

[mapbike]

That first ride is always the coolest... What happened tho? why did it die?

For me, today I took mine up the street to my favorite taco resturaunt for breakfast, but didn't turn on the gps to record the top speed... just rode it to enjoy it.
Then I had a few free minutes at the shop so I took the front wheel off the new bike to chean up the bearings and re grease them, found a bit of roughness in the front bearing so I took it all the way apart and cleaned everything to see if it needed new balls or if the races needed replacement, luckily it's just a nick in one of the outer races and I got a few spares...

sounds like fun Dave, only problem for me is that a quick run to the nearest taco shop for me is a 20 mile round trip ride....lol.!

I did ride about 22 or so miles yesterday on the new half breed mill but none today, just knocked .060 off of a jug deck and and then thought about all of it a bit more....

 

[Davezilla]

My problem is just the opposite since the taco shop I go to is only about a mile down the road... not even far enough to warm up teh engine so I usually have to sit at the shop and warm up the engine for about 10 minutes if i want to do a speed run, then while I'm in there waiting on the food it usually takes around 10 minutes to get the food so the engine has enough time to cool back down... What wuold be really nice is if I had a 4 to 5 mile stretch so I could get it nice and hot right before I get on the throttle, it does tend to run a lot better after it's fully warmed up and the 4 stroking goes away for the most part, just a little blubbering at around 20 to 25 mph then it cleans up and goes... I'l tune it better after this tank is done since it seems like the rings are seated pretty well already and the bike kinda leveled off at around 41 to 42mph on top. I did get to see it go from 35mph at best to 38mph, then to 40, then to 41 about 2 weeks ago and I'm about 3/4 the way thru my second tank so it's real close to time to properly tune it.

.060" sounds like a lot but I had to cut out .040 or so just to true mine up, then I went back in and cut out another .012 to get the squish clearance on my first engine, as well as another .040 off the base to get it trued up, it trued up somewhere around .037 if I remember right so I just cut it up to .040 so it would be easier to keep track of how much I cut off. Then when I transfered this jug to the Dax bottom end the piston was sticking up past the deck by about .040" but I made up for that by using a .040" spacer, then I ended up ditching the spacer in favor of 2 .025" copper gaskets glued together with a very thin layer of shellac right before final assembly and torquing along with a single .016 and a single .025" copper gasket sealed the same way up top to set the squish in range.

 

[GoreWound]

That first ride is always the coolest... What happened tho? why did it die?

not sure, but I think the clutch let go, maybe it needs tightening. didn't bother trying to figure it out yesterday because I had exhausted myself pedaling it back home.

planning on taking a better look later today.

 

[Davezilla]

Ouch... that happens to all of us... I learned to keep my maiden voyage close to home... as well as the next several rides just in case something went south on me.
Anyway, hope you get your clutch sorted out, on these things it could be anything from a loose cable to grease getting slung up from who knows where and onto the clutch pads, could also be the flower nut wasn't locked down and backed out some... but you'll find it, these things are at least simple enough for quick fixes.

For me... Today has been unbeleivably slow and boring here at the shop so I set up the bearings on the new rim with the disc brakes, cleaned and lubed with Kendall Super blue which is an ultra heavy duty bearing grease I use on big truck bearings, but also use on anything else that needs grease, this stuff is slick, it stays put, and will most likely outlast that wheel I just built up... Enough on that.. My next problem to overcome is getting the caliper mounted on the front fork lower... This is proving easier said than done so I went thru my calipers to see which one would be the easiest to adapt to a fork that's not set up for disc brakes. Caliper #1... came off the other bike, has little tiny pads, but they work good. This one would be the trickiest to adapt to my forks so back on the shelf it goes... Caliper #2... came off a pocketbike rear brake... very large pads and very well built, but too bulky, too much needs modified, and it really needs a thicker rotor. Caliper #3... came off a pocketbike front brake, this one has nice sized pads, about twice the size of the small round pads the bike came with, full floating design so I just need to make a single flat bracket and it'll tuck in nicely on the back side of the fork leg, looks good once installed... Yup... this is the one I'll be using... Soooo... if today continues to be slow and boring over here I might just fire up the plasma cutter and make me a bracket... I got the measurements and reinstalled the old front wheel so the bike can remain functional while I'm working this brake situation out.

 

[GoreWound]

Davezilla, sounds like you are building a sick machine there, I hope your braking power is magnificent!

I did some further mucking around on the bike, I think there was no key holding the drive sprocket to the shaft. that or it turned to dust. either way I need a new one. considering finishing the takedown of the clutch assembly before calling the guy who sold me the bike.

 

[Davezilla]

That could very well be the problem... either they never put a key in it on the assembly line and somehow it held this long or the last guy lost it, these things will go for a while without a key if the gears and sprockets are a nice tight fit... but not very long.
I know on the centrifugal clutch kits the key can't be used at all on the crank because with the bevel gear removed and the shaft extension installed, all that keeps the shaft extension from slipping on the crank is just that slight taper on both parts, then when torqued down it don't slip. I've had my bike up to 38mph without a slip at that connection, but what did make it slip was when the gear separated from the clutch bell.

I would buy a replacement key, but buy a few more just to keep on hand as spares in case one goes flying out during disassembly or reassembly, they hold just fine once installed, but get lost real easy.

 

[GoreWound]

I doubt a cut-off piece of coin would work, would it?

Edit: I sent an email to the vendor asking if he might just send a replacement.