After exhaust mod...cutting out at top-end.

[misteright1_99]

I think I'm having the same problem as mark...my engine seems like it is running too rich, my needle is on the lowest setting and just for kicks I took the airbox off and ran it for a bit; this all made my engine run better, still rich, but not as rich. When I moved my circlip to the 3rd position on the needle (from the blunt end) it made it far worse, I couldnt accerlerate and had very little throttle response. I rejetted my carb and this was even worse. So oviously way too rich.

How do I solve this problem? Increase air flow somehow? Do I take the O-ring out and leak air in?

What size jet was stock, and what size jet did you rejet to?

 

[Pablo]

I think I'm having the same problem as mark...my engine seems like it is running too rich, my needle is on the lowest setting and just for kicks I took the airbox off and ran it for a bit; this all made my engine run better, still rich, but not as rich. When I moved my circlip to the 3rd position on the needle (from the blunt end) it made it far worse, I couldnt accerlerate and had very little throttle response. I rejetted my carb and this was even worse. So oviously way too rich.

How do I solve this problem? Increase air flow somehow? Do I take the O-ring out and leak air in?

What happens when you put the E-clip in the leanest (top) groove?

What is telling you that your engine is too rich?

 

[JohnnyLoves]

When the E-Clip is on the leanest setting it runs better, than the richest setting. More throttle response and feedback. The engine also has a more consistent tone, less sputtering. The spark plug also burns amber, "tanish", with a few black oil deposits.

I thought everyones stock jet size was the same to start with? I drilled it slightly larger using the smallest drill bit I have which I believe is 1/16.

 

[misteright1_99]

You cant expect to get any kind of good results drilling your jet out to 1/16. These jets come in sizes in steps of 1/100 of and inch increments......

 

[Pablo]

1/16 is HUGE. .0625 = 1.58 mm

Actually the jets come in .01 mm increments

Maybe you meant 1/32 but even that would be a bit too fat.

stock is .70 mm which is 0.028" or so

1/32 is about .79 mm......so that might work....but a little phat at WOT.

 

[Marktur]

Yeah, I think I'm going back to the second notch (leaner) and my new jets should be here shortly... I also realized last night that the bell on the throttle body of the carb was loose. I tightened that back down, and now I have to pedal with the motor to about 15mph before it takes off, and really jumps on the pipe at 28mph.

So for high end, yes, it likes richer settings...but it takes me 2 city blocks to get going now...I'm going to make the switch before I ride home...

A carb with 2 needles, low and high, is the real answer. Pablo - what did you get?

Also to answer Pablo's questions:
Ported to match the motor only.
Stock pipe
No, haven't even looked at the jet yet.

Thanks guys!
Mark

PS. Did some shopping around last night...it's a HUGE jump in price from HT to "named" motors. You can buy a killer scooter for the same price...and have something that will do 60mph, is built for it, full lighting, etc. Personally I'm happy doing 25-30 on my bike, but I'm also tired of the aggravation and daily "changes" in performance.

I dunno....I'll work with this for a bit more and see...not ready to give up yet, but back to that "I dunno" stage again...

 

[Pablo]

I got a knock off Delorto type. Of course it will need tuning as well....

There is only so much you can get out of the stock pipe and stock carb. With an expansion pipe the powerband can be shifted by changing the prechamber length and is widened a bit...low end grunt is good, but there is a step in power at a certain RPM when it comes on the pipe. It takes some throttle skills and is not necessarily the best thing for traffic conditions in a one speed bike.

The stock carb can be a PITA, but mine, less a different jet or sanding the needle down does pretty good.

I have no idea how setting the new carb up will be like.....I'm a bit torn right now as to when/how I want to approach it vs. messing with the needle of my stock carb.

Changes in performance will occur until the engine is well broken in.

 

[kaploink]

When the E-Clip is on the leanest setting it runs better, than the richest setting. More throttle response and feedback. The engine also has a more consistent tone, less sputtering. The spark plug also burns amber, "tanish", with a few black oil deposits.

I have found the leanest setting to work best on mine. It seems like I could even go leaner due to it still running slightly rich. I finally tried the lean setting after having constant problems with the motor running far too rich. I was reluctant to try the leanest setting since it seems to be a taboo setting that would destroy the earth as we know it.

I would almost assume that the carb was set up to run rich enough to cover the unsealed intake leak at the carb if it wasn't for all the people that seem to have problems with it running lean. Though, the unique quality control on the engine kits is probably a factor in the differences.

 

[Pablo]

I have found the leanest setting to work best on mine. It seems like I could even go leaner due to it still running slightly rich. I finally tried the lean setting after having constant problems with the motor running far too rich. I was reluctant to try the leanest setting since it seems to be a taboo setting that would destroy the earth as we know it.

I would almost assume that the carb was set up to run rich enough to cover the unsealed intake leak at the carb if it wasn't for all the people that seem to have problems with it running lean. Though, the unique quality control on the engine kits is probably a factor in the differences.

Quoted for righteousness. Seems to be what works for me as well.

 

[Marktur]

OK, I think I got to the bottom of the problem. I still have a little bit of a boggyness at full throttle, but that's fine - I think it's just a little to fat at the high end, but that's fine, protects the motor...

The best thing I've done so far was my latest change last night: I replaced the head gasket with one from Dax. It's Like a new motor today!

I'm also running AMSOil 3oz/gallon - about 38:1 or so...I had it richer, but I don't think that's necessary with this quality synthetic stuff. I've played with the mixture on the carb...tried all slots, and I think it's happiest at the STOCK break-in setting (2nd ring from the top - blunt end).

I've also ported the intake and exhaust to match the motor, and also trimmed up NEW gaskets as well...finally, an o-ring in the carb/manifold connection to seal it.

My bike is running GREAT now! I'm sure I can keep tweaking it for the little bit more at WOT, but I back off at 30mph anyway...and it wants to keep accelerating! 3/4 throttle delivers the most power through 20mph, then I open it all the way to continue the strong acceleration. It's always a trade-off with only 1 needle adjustment..even with RC airplanes and cars, too.

So I'm good, happy, and ready to ride!