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Post by oldchopperguy on May 12, 2009 23:11:04 GMT -5
OK guys, my Xingyue Eagle 150 "driveability" just went south after 1,000 trouble-free miles.
Starts and idles fine. But at more than slightly open throttle (about 8 mph) it stumbles and won't rev. No fuel. Just "sucks air". No backfire, just sounds like an air compressor until you go back to nearly closed throttle. Then it runs fine.
Checked all fuel and vacuum lines, petcock, plenty of gas in the float-bowl, no vacuum leaks... I pulled the carb and manifold, no cracks or leaks there. I figure the carb has a broken diaphragm, or maybe a clogged jet or fuel passage. No time to work on it this week, but any advice is welcome.
This Reb needs to get his hoss back on the trail...
Thanks!
Leo in Texas
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Post by Rebel on May 13, 2009 0:30:10 GMT -5
You didn't say anything about the fuel filter, is it clear?
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Post by oldchopperguy on May 13, 2009 9:14:35 GMT -5
Yes, the filter's new and working OK. Plenty of gas getting into the float bowl, but not into the engine... I haven't checked the valves yet, but it idles smooth and runs fine until the throttle is opened. I suppose a sudden change in the intake valve barely opening might cause this, but it seems like classic "bad-carb" syndrome. I'll check the valves to be sure.
When I get some time, I'll take the carb apart. I suspect the problem will be obvious, unless it's clogged internally. Not likely that both the low and high-speed jets would be suddenly be blocked. It just won't take throttle at all. Acts like a catastrophic vacuum leak, but all checks out externally.
I checked the spark plug while I was at it and surprisingly it is a nice gray/tan. It's not even running too lean on stock jets.
I see there are genuine Japanese Mikuni carbs for the GY-6 150, complete with hookups and choke, etc., available now on eBay for around $75 delivered. These used to be well over a hundred bucks. Sounds like a GOOD investment! Might prevent some headaches down the road...
Thanks!
Leo
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Post by harrywr2 on May 13, 2009 9:32:36 GMT -5
Airbox on tight? No cracks in the airbox? All the hoses connected to the airbox on good? If I disconnect the gear box vent hose from the airbox I end up with lean stumble.
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Post by oldchopperguy on May 13, 2009 22:59:41 GMT -5
harrywr2,
Yes, all checked out. Also tried removing ALL peripherals (air-pump, all vents, EVERYTHING to the airbox) and blocking appropriate places on the engine and carb, leaving only the vacuum line from the intake manifold. No change in running. It's just getting very little fuel through the idle jet, and NONE through the high-speed jet.
Could be the Chinese fuel lines have begun to decompose from the inside, and are clogging the carb with goo. I'm buried with work all week, but as soon as I can, I'll replace all lines both fuel and vacuum, and inspect the carb. Still could be a bad diaphragm. I believe I will upgrade to a Mikuni carb while it's apart. THAT should solve the problem...
Many thanks!
Leo in Texas
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Post by therustyaxe on May 18, 2009 2:03:08 GMT -5
This just my opinion, I say "VALVES". Check the valve gaps. If it is sucking that air and can't expel it, the first thing to check is the exhaust valve. Since you have the cover of check clearance on both. My exhaust valve came WAY to tight from the factory. That should solve the prob. Also, Mikuni Carbs, I love them! I called them a few weeks back and asked them for two stickers. Much to my surprise, I got an envelope with about 100, lol They are excited to here how much they are being used on scoots. Get the carb, worth while investment.  |
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Post by kliff on May 18, 2009 14:02:07 GMT -5
Valves and fuel lines.....adjust, and replace, then put about 2-3oz of sea foam to a full tank of premium gas, and go for a ride, a LONG ride...like enough to use that tank of gas, then fill up again, and see how she does...oh yeah, throw in an NGK 7544 plug too.
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Post by oldchopperguy on May 18, 2009 22:34:16 GMT -5
ALL good advice!
As soon as I get through some medical things with the wife (another week or so) I'll get at it! All new hoses (both fuel AND vacuum). Remove ALL unnecessary hoses and devices, like kliff shows on his new scoot PDI thread... ESPECIALLY that horrid chrome tube/rubber hose reedvalve setup off the head. The rubber on that thing split, and that started all this nonsense to begin with.
Some RAW EXHAUST actually exits that monstrosity. I even checked out the local mower shop to see if that was "normal". He assures me it is... Pulled the hose off a John Deere to show me, and let me hear the blast!
He also assures me that raw exhaust blasting through the rubber hose is a real bad idea. Exhaust belongs in the EXHAUST system, not blowing back into Lord knows where!!! All that's needed is vacuum where vacuum belongs...He agrees: BLOCK IT OFF and remove/plug the entire mess and wherever it blows into. He does that routinely on lawn equipment with large engines having such "features" to improve reliability.
If it's good enough for John Deere, it's doggone-sure good enough for Xingyue!
New plug (surprise: the current plug does NOT show too-lean mixture!) adjust valves, and new Mikuni carb... THAT should get "Lil' Bubba" back on the road again. Gotta get her done... The docs are getting my Wife in good shape, and she's wanting to hit the road!
Many thanks as always for the advice!
Sincerely,
Leo in Texas
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Post by Rebel on May 18, 2009 23:33:49 GMT -5
ALL good advice! ESPECIALLY that horrid chrome tube/rubber hose reedvalve setup off the head. The rubber on that thing split, and that started all this nonsense to begin with.Some RAW EXHAUST actually exits that monstrosity. You're not talking about a crankcase ventilation/blow-by are you? Blow-by looks a lot like exhaust but occurs naturally in ICE motors. I'd vent that but not plug it. |
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Post by oldchopperguy on May 19, 2009 12:38:53 GMT -5
Rebel,
I don't think so, it appears the crankcase is vented elsewhere, but I'll definitely double-check to be sure. This is the fitting on the head/valve cover that works with a reedvalve in conjunction with the emissions control stuff. Kliff shows how to make a plug for it on his thread on PDI on a new Eagle scooter.
The small-engine mechanic I visited showed me the same setup on a large lawn tractor. Says it's designed to divert SOME (?) exhaust back into the intake system for "cleaner emissions". He said at least in Texas, there's no rule against losing the entire system (as it appears Kliff did in his thread) so it's going... What a "Rube Goldberg" gizmo!
I'll probably be checking with Kliff just to be sure I'm not missing anything in the process...
Hey, I REALLY like "Rebel" in his new gray uniform! Me fer some fried chicken and insurrection! Now, just where'd I leave Daisy Duke...?
YEE HAA!
Love this new site,
Leo in Texas
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Post by kliff on May 19, 2009 17:15:57 GMT -5
Rebel, I don't think so, it appears the crankcase is vented elsewhere, but I'll definitely double-check to be sure. This is the fitting on the head/valve cover that works with a reedvalve in conjunction with the emissions control stuff. Kliff shows how to make a plug for it on his thread on PDI on a new Eagle scooter. The small-engine mechanic I visited showed me the same setup on a large lawn tractor. Says it's designed to divert SOME (?) exhaust back into the intake system for "cleaner emissions". He said at least in Texas, there's no rule against losing the entire system (as it appears Kliff did in his thread) so it's going... What a "Rube Goldberg" gizmo!I'll probably be checking with Kliff just to be sure I'm not missing anything in the process...Hey, I REALLY like "Rebel" in his new gray uniform! Me fer some fried chicken and insurrection! Now, just where'd I leave Daisy Duke...?YEE HAA!Love this new site, Leo in Texas There are severral types of emissions controls, EGR, exhaust gas recirculation, where exhaust id routed back to the intake, and the PAIR.....sumpin' sumpin' sumpin'.....which using a reed valve and manifold pressure, actually injects fresh air into the exhaust. This give any unburned fuel in the exhaust an air source, to complete the burning of unspent fuel, in the pipe. Tha PAIR system is what we have. It uses no horsepower to operate, nor does it restrict the engine. It complicates engine plumbing, allowing even more tubing/connections to cause intake leaks, and makes the exhaust run at higher temps, causing premature weld failures, due to the additional extremes in temps the exhaust system will see. As this injection of air occurs in the exhaust port, it will also serve to raise head temps. This is the biggest detriment we face, with an active PAIR system. HTH's... |
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Post by oldchopperguy on May 20, 2009 2:01:25 GMT -5
Kliff,
I've got a lot to learn about these engines... Not like a vintage Harley pan-head for sure! This fitting I'm describing is the same one you show how to plug with a machined aluminum plug in your PDI thread. I just can't work on it until sometime next week. I still need to study the plumbing around the carb, intake, etc. to be sure I don't remove or plug something that's actually necessary.
Any do's or don'ts you can pass on to me will be greatly appreciated. Feel free to PM me if the info is superfluous to the site. If it's stuff everybody should learn, please do post for all to see!
Fortunately, I sniped a brand-new Mikuni carb with all hoses and electric choke off eBay for $32 + $15 shipping (I figured THAT was a bargain...) so Lil' Bubba will get a nice new carb transplant while apart!
Thanks much for your advice!
Leo
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Post by kliff on May 20, 2009 16:52:47 GMT -5
Oh man...where to start...lemme tell you what I ended up with. One vacume line from the intake, to the upper carb vacume port, the other vacume port on the manifold plugged. Other than the flange I used to cover the plug I made, everything else, to do with vacume or the PAIR system is gone.
Vacume petcock is gone too, manual now.
MRP makes a PAIR block plate, to bolt on the head, where I made the plug, Jeremy@Environmoto, or Pedez at Sunl.com both are MRP dealers, and should have in stock, or be able to get that part.
Hope this helps...
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Post by theswede on May 20, 2009 17:02:49 GMT -5
I blocked off my PAIR with a piece of copper sheet essentially like the block plate Kliff mentions, but home made.
Really simple, and copper is easy to work with plus it will deform some making the plate seal.
Just remove the pipe where it bolts on to the head, cut the copper sheet to overlap the hole into the head and the two bolt holes, then drill out the holes in the plate. Use some high-temp liquid gasket to hold the plate in place, put the PAIR pipe back and tighten down the bolts.
No more PAIR. Simple as that.
/Otto
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Post by oldchopperguy on May 20, 2009 22:03:05 GMT -5
Guys, you're the BEST!
A bone for all... (OOPS! I mean a big YEE HA!)... Gettin' old, memory slips out of gear...
Sounds like your scoot has about the same PAIR setup as mine. I'll make a simple block-off plate to expedite the repair, and make a nice one when time allows. Already have manual petcock, filter and lines. New carb is in transit. As soon as I get some time, I'll get it together and see how it runs.
I have new air-filter and performance exhaust too, but one thing at a time. Gotta get it running right first, then change other things around. Always best to do one thing at a time to avoid that "What alteration did I mess up" syndrome!
I'll be glad to get this scoot back on the road. It's been a real joy to ride until the meltdown, and that seems like it should be a simple fix.
Thanks again!
Leo in Texas
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CAN YOU HELP ME OUT MAN,AS i LOST ME JOB DUE TO NOT BEING ABLE TO GET THERE?ANY INF