Need Help w/ Erratic '96 KLF220 After Rebuild

[stevetro]

Hi all,

I just rebuilt a 1996 Bayou/KLF220 which included the following:
-Rebuilt Head (new valves, cleaning, etc done at a shop)
-New Rings (cylinder and piston looked fine)
-New wiring harness (mice ate old one) Triple-checked that this is installed OK
-Rebuilt carb (cleanout,new jets, float needle, etc.)

I performed most of this work. I'd say I'm not a natural small engine mechanic, but I follow manuals well and consider myself pretty handy and have successfully done this type of work in the past.

After this rebuild and attempts at starting the quad, I found the following:

-The pull starter/recoil is extremely hard to pull even with decompression lever pulled. I have to use this as I don't have a new battery yet. I never remember it being this hard. Recoil appears to be setup fine since it does spin easier with spark plug removed, but still not like butter.

-The quad actually did start, but is running extremely rich - new plug is super black after just a few minutes. With pilot and idle settings proper, the engine will barely go past idle with the throttle nailed. I'm sure cable adjustments are fine. It reacts as if the choke is on, however the choke is working correctly and is not having any effect on the idle. Float should also be working OK, I'm not getting any overflow.

Here's my concern regarding the head and timing: With the head returned from the shop, the 2 valves are obviously seated and closed. So combining this with turning the flywheel to be at the proper TDC mark, and the cam able to be propely slid into place, cam sprocket properly aligned and tensioner properly set; its my understanding that this was installed correctly and sitting at TDC before attempting starts?

If for some reason I have the engine set 180 degrees out of phase, would the engine actually start, and perhaps react the way I described?

I'm planning to pull the cam and valve covers and re-validate the timing setup, but would hate to pull the engine out again. Another observation but not sure if it means anything; while diagnosing idle/acceleration, I removed the air cleaner and can see puffs of air/fuel shooting in the direction of the airbox (backwards). If I attempt to block this flow with my hand, I observe the idle shooting up to almost normal. It seems I can only do this once before the engine bogs and shuts down. Just thought I'd mention that.

I'd greatly appreciate if any experienced engine rebuilders could comment on this situation.

Thanks much, Steve

[RCW]

Timing 180 degrees off will not allow the engine to even start.

However, the timing being off a few degrees from a missing or sheared woodruff key at the flywheel, or the chain being off a tooth will do as you describe.

I would realign all the timing marks all the way to the camshaft, and I would bet you are off slightly.

[99prairie400]

With the engine 180 degress out of time it would not run at all. You would get loud bangs and small explosions out of the intake manifold. The spark plug would be firing during the "overlap" period between the end of the exhaust stroke and the beginning of the intake stroke. The cylinder, would of course, be filled with unburnt gasoline and flame would rush out of both ends. The bang would be the fire out the tailpipe, the small explosions inside of the airbox, fairly self-explanitory.

Now, what could have happened, was the timing chain tensioned to the wrong side before releasing the auto-tensioner which would basically result in the timing being a tooth (or possibly more depending on the exact geometry of your timing chain tensioners) off of the proper marks. If you were a tooth (or more) off time it would cause it to run poorly.

[stevetro]

Thanks guys for the response. I'm going to check the timing marks again; never did consider that the tensioner would now move the cam sprocket slightly to the right when released. I'll experiment with that.

Any idea why pulling the engine manually would be so hard? Maybe just high compression with new valves, etc. and un-broken in engine?

[99prairie400]

Did you turn the lower end over without the cylinder in place?

I had the timing chain "wired" to the handlebars to keep it from falling down inside the crankcase on the Prairie 400. When I put the new piston on, before I slid the new jug down, I turned the crank over a bunch of times.

#1 it pumps oil into the filter/delivery holes before cranking keeping you from having a dry start.

#2 It ensures that the case bearings/rod bearing isn't too tight.

#3 It ensures that everything is lined up (and nothing fell down into the crankcase) during installation that is going to cause trouble when you try to crank it.

If you didn't turn it over without the jug on the only test you have is to remove the spark plug and pull it over. It should be a LITTLE tight because of the new rings on the hone marks but it shouldn't drag. If it's dragging there is probably something wrong. Either something wrong with the piston (damage to the skirt, damaged ring land) the cylinder (wear marks you didn't catch with it off) or the crank (case bearings are pinched, wrist pin is gouged to the small end of the rod)

[stevetro]

Yes I did turn it a few times, maybe 10? but not as a conscious effort to address your points 1,2,3, but more than likely just out of interest to ensure the chain was properly riding on the crank.

Also, forgot to mention the wrist pin is also new. (I'm more used to 2 strokes so it still blows me away that 4 strokes don't require upper crank bearings - I know, alot less revs!)

Also moved the piston a bunch with jug on and head off, so I'm sure rings are set OK, etc.

It might just be my imagination on the pulling required for the recoil... but my strong 22 year old was also ****ed at how hard it was to pull that sucker, but we did get it started this way.

Again - Ill go over the timing setup once more and test 'er out.

Thanks again.

[86klf300guy]

hello, when you replaced the rings did you gap the rings correctly?
a oversized ring or not gapped correctly would cause a hard pull,due to to much tentsion against the wall.

when i rebuild a engine a put the piston back in to the jug and i lightly oil the jug ten i roll the engine over by hand to make sure everything moves freely.then put the head on timing chain and set timing and then adjust valves ,then spin it it over by a socket& rachet a few times to double check timin and see if anythings binds up then i richin the fuel mix a little and fire the machine up and let it idle for 5 minutes shut it down and let it cool.

try this on your machine take a cap full of 5w30 and put it down into the cylinder let it set for a couple of minutes and see if it frees up on the pullin.
if you did not oil the new rings and put it all together dry it will bind.

i know sum peeps do the dry fit and have no issues but id rather have sum lube on new rings on first pull than dry less chance of breakin em.

if it still harb to pull take the timin chain off the cam and then pull the engine over and see if it still binds up.if so you may have to pull the head back off and take a good look at your rings.if you didnt have the piston clean the ring lands may have had carbon build up on them and causein the rings not to set in the lands properly.

-corey-

[stevetro]

Latest Update: Most problems solved, but some small new ones.

I removed the cam tensioner, cam, rocker arms, and sprocket and started the process all over again getting things lined up. I must have been off a tooth or something, because I did this now the second time much more carefully and made sure the cam was located right smack in the middle of it's free turning happy zone and then lined up all marks and set the chain and tensioner appropriately. Re-adjusted the valve clearances since they measured tighter than the specs.

It works! Revs up nicely, so I know I'm lined up properly now. The pull started is also easier now, I can only chalk this up to the valve clearances.

I also got the battery/starter circuit working properly (and that's after a new wiring harness install, so I'm proud of that)

But of course a new issue. She's back popping a little and slightly backfiring as she down revs after hitting the throttle. Also running lean from what I can tell from the white-ish plug color. Idle also appears to idle

Carb is all clean and new jets all set propely, air screw also. Pilot circuit appears to be all clear when using carb cleaner. I'm suspecting the carb to airbox boot since it just doesn't quite fit properly no matter how hard I try to fit it and clamp it down. Looks to me like it has shrunken over time since where it clamps down is not quite a flat circle but more angled so it really fights a good clamping. I have one on order. I hope its not my imagination, but it appeared to not pop when I reved it up and sprayed this area with carb cleaner.

I now broke the choke plunger so I also have a new plunger and o-ring on order. I'm also going to test the spark when I get a chance to see if it's strong enough. (book says it should be able to jump blue about 1/4 inch)

Questions:
If I understand correctly, my symptoms indicate too lean of a mix and/or weak spark?

If an intake leak could be the issue, is it more likely before or after the carb for it to have the backfiring symptom?

Could a carb slide being out of spec produce these results? This sucker is expensive and I can't find an after market one on ebay or anything. The reason I ask is I'm not sure what a new one looks like, but mine appears to be half brassy chrome and half black, as if some sort of black teflon coating or something has worn off over time. Does respond to idle adjustments though I'm going to hold off on the slide and fix the boot and choke and test the spark first.

Thanks again KLFGuy for your help and concern. -Steve

[stevetro]

Originally Posted by stevetro

But of course a new issue. She's back popping a little and slightly backfiring as she down revs after hitting the throttle. Also running lean from what I can tell from the white-ish plug color. Idle also appears to idle

I meant to say: "Idle also appears to wander"

[86klf300guy]

id fix that choke plundger right away that will cause your intake leak.and cause a lean condition and idle wondering.

glad to hear it was only the cam and timing causein the hard pull etc.that was a lot easyier to repair lol.

-corey-

[stevetro]

Well, it's still not right.

I replaced the choke plunger and O-Ring, and the airbox to carb boot. The boot was a great fix since it fits so much better than the old shrunken and hardened boot. No leak coming from there.

Bayou starts right up now and idles fine without the choke, but within 5 minutes its overheating to the point that the header pipe glows red in the garage darkness. While idling, it will infrequently stutter, and after reving will tend to pop and backfire slightly. I'm using the Haynes manual for my guidance by the way.

I've also checked:
- Carb to head intake boot appears free from leaks and the o-rings are new.
- I've measured the carb float height and swear it matches what is documented in my Haynes manual.
- Spark is strong, tested that it can jump blue over 1/4 inch.
- External oil lines are free from debris.
- Oil capacity is also on the mark.
-Carb is really clean and pilot circuit flows free - no boken air screw tip.
-Air screw set stock at 1.5 turns out.
-No exhaust leaks.

I have what appears to be a lean condition since the plug is somewhat white, or do I have oil flow issues that can appear as a lean condition?

I'm stumpted!

What is more likely to cause this overheating issue so fast? Lean from lack of fuel flow, or engine lubrication? Remember, the head is rebuilt with brand new valves as well.

Any ideas?

Thanks again!!

[MrGiggles]

Originally Posted by stevetro

Well, it's still not right.

I replaced the choke plunger and O-Ring, and the airbox to carb boot. The boot was a great fix since it fits so much better than the old shrunken and hardened boot. No leak coming from there.

Bayou starts right up now and idles fine without the choke, but within 5 minutes its overheating to the point that the header pipe glows red in the garage darkness. While idling, it will infrequently stutter, and after reving will tend to pop and backfire slightly. I'm using the Haynes manual for my guidance by the way.

I've also checked:
- Carb to head intake boot appears free from leaks and the o-rings are new.
- I've measured the carb float height and swear it matches what is documented in my Haynes manual.
- Spark is strong, tested that it can jump blue over 1/4 inch.
- External oil lines are free from debris.
- Oil capacity is also on the mark.
-Carb is really clean and pilot circuit flows free - no boken air screw tip.
-Air screw set stock at 1.5 turns out.
-No exhaust leaks.

I have what appears to be a lean condition since the plug is somewhat white, or do I have oil flow issues that can appear as a lean condition?

I'm stumpted!

What is more likely to cause this overheating issue so fast? Lean from lack of fuel flow, or engine lubrication? Remember, the head is rebuilt with brand new valves as well.

Any ideas?

Thanks again!!

It sounds like it is just running too lean to me. Turn the pilot mixture screw out 1/4 turn and see what happens.

[zeek123]

hey steve could you take a look at my post about my bayou 220 to see if you could help me