Honda Spree and Elite 50 Forums

hey folks,

have an odd problem on my purple elite. flat out WOT on straight is fine, uphill is fine, down slight grade is fine. BUT any steep downhill and it starts to hesitate, intermittently, feels like fuel cut. i can back off throttle and its good, then back to WOT and starts hesitating, again ONLY down steep downhills. pretty certain issue is carb and not ignition related.

motor setup is as follows:
70cc malossi sport cyl, 8.44:1 gears, stock unrestricted SA50 exhaust, kymco zx50 intake (shorter) w/ CF reeds, aftermarket stock type carb upjetted w/ open UNI filter

my thinking is something is not quite 100% w/ the stock type aftermarket carb.. float height perhaps? going to pull apart and investigate, have at least one spare float to try, is there any way to adjust it on stock carb? any other ideas?

appreciate any input

Whats your temps at.

haven't checked on this one. jetting is conservatively rich, plug on black side. exact same setup worked great for miles and miles of WOT on a kymco zx50, except w/ tecnigas Next R pipe. hard to imagine this issue is pipe related tho.. believe issue was there too with the nextR, but it was less noticeable.

When hesitating does it back fire or bog anything like that?

Your notion of a fuel related problem seems the only logical conclusion.
Take a good look at the design of the carb to determine if the
skewed level of gas in the bowl will starve the main jet assembly, as a whole.
Another possibility might be that gas is being "spilled" into the throat creating a rich hesitation.
Subscribed...mm...

I ride my stock carb bike down a 13k mountain road dropping to 9k by the time were done. Never had an issue. Your plug will tell you if you're having fueling issues.

MrJumps wrote:When hesitating does it back fire or bog anything like that?

no backfire or bog, just hesitation kind of like a rev limiter but more akin a slight fuel cut

1man8scoots wrote:I ride my stock carb bike down a 13k mountain road dropping to 9k by the time were done. Never had an issue. Your plug will tell you if you're having fueling issues.

ya im with yo on that, never had any such issue w/ all my other bikes and stock Honda OEM carb. don't feel super confident about this copy carb, but trying to make it work.

motormike,
just bought new fuel & vac lines, plus may throw on a fresh filter just to ensure fuel flow from tank is good. def feels its lack of high rpm fuel deliver somewhere in the circuit. just to note, when i removed vac line at petcock, there was small bit of gas on it, that shouldn't be. may try diff petcock too. will update

I would try to borrow a cht or buy one that still sounds possibly a seize. My bike is doing a similar thing as your describing and my initial thoughts are a seize but today when i scoped my bore it showed some small scratches. Better safe than sorry, grab a cht. Also if its only when downhill? That could be just a clogged petcock filter.

MrJumps wrote:I would try to borrow a cht or buy one that still sounds possibly a seize. My bike is doing a similar thing as your describing and my initial thoughts are a seize but today when i scoped my bore it showed some small scratches. Better safe than sorry, grab a cht. Also if its only when downhill? That could be just a clogged petcock filter.

very certain its not seizing. had soft seizes with smaller jet sizes much earlier, but im up at like ~98 (edited* was ~102, but ~98 is more accurate) and on flat can hold WOT all day w no problems

swapping petcocks and there was actually no in-tank prefilter behind petcock.. lol so thats not issue.

tore stuff apart lastnight, hope to cobble back together today and get some results

stumped. and baffled. is what I am..

So far have tried: new fuel/vac lines, no filter/new filter, adjusted float bowl. these things did nothing. noticed spark was "leaking" as in you could place hand near wire/boot and it would arc and shock your hand, So also replaced: new plug, new ignition coil & wire, new NGK plug boot. fixed arc issue, but hesitation problem persists.

finally decided to chuck aftermarket carb aside, and threw on genuine Honda Keihin carb anticipating positive results. NO Dice! Same dam thing..
pretty frustrated at this point, almost ready to throw in the towl

to add to the hesitation at speed, noticed you can also hear an intermittent sucking sound coming from the open filter, still akin to fuel starvation?? sounds like

have one maybe 2 more things to try:
bypass petcock entirely, with an auxillary fuel cell & carve up a main jet larger than current

motivation is slim tho

You should run the stock air box. I ran stock modified airbox and carb on my set up, I'm at 5800 elevation, and I ran a 90 jet and was almost rich. Down at lower elevation it runs a 92 jet. These little carbs need the airbox.
I can run mine up to 12.5k no problem but with the wild lion it really like 8600 rpm with the cast iron. At 8900 I'm at 60 mph consistently.
If you insist on using the open pod filter try up jetting but it will always be a pain I bet.

Agree with the stock airbox x100. My Aero ran funky when I got it with a pod, runs so much more consistent with the stock airbox, world of difference. More air carries more gas, but if the amount of gas it needs isn't there, the engine can't do it's thing properly, it just gets lots of extra air in the mix causing the leanness. A lot of sizes of Honda bikes seem to have this type of impact with pods, I have a Cb650 with the same impact with anything other than stock. Keihin engineered the carbs to run with the airbox, so changing that can force a lot of really tedious tuning or improper performance in the interim.

stock airbox may in fact fix things. i have it, but was hoping to save it for a separate prj, plus like the sound with the open filter. will tweak a bit more and use this as last resort.

graphite9,
building this for a friend and have already sunk more into it than anticipated, so trying to stick to stock carb n whats on hand.