Plug bone dry after top end rebuild=no fuel past carb

[crazy3rdgen]

hey guys , today I put my new wiesco top end kit together and everything went great. Once it was all back together and bolts torqued it was time to kick it over. Nothing. Pulled the plug, dry as a bone. So we experimented by dropping some gas in the cl and it would run if you kept the rpms up but then die. For some reason no more fuel coming to the engine. The reeds were dry as a bone as well. Any suggestions on how to get my bike running right and kicking on the first few kicks. When we did put gas in the cl threw the spark plug hole and kick it... it was running great! But didn't last too long. Now it won't even start by doing that. We have spark.

 

[kelsorat]

Sounds like you have no compression. A 98 CR125? Did you buy it used?

 

[crazy3rdgen]

It's a brand new top end rebuild, I can feel the compression difference compared to before hand.. I give it a good amount of gas and it pulls up more then it ever did but then when rpms get low it just dies. Kinda like fuel isn't getting there fast enough. Yes I did buy it used...

 

[crazy3rdgen]

oh yeah, and I check my reeds.. Some of them aren't closed... I can see light threw most of the reeds..

 

[kelsorat]

Even if your top end is brand new, and especially in the case of a 125, you should have measured the bore. The rings and piston must match the bore. 96-99 CR125's have 8 different bore sizes, meaning that you could potentially overbore a stock cylinder 8 times. Do you know the Wiseco P/N?

 

[crazy3rdgen]

I did the order from motosport.com put in my information. I inspected my nickle plated cl wall and you can still see the cross sectioning in it. Everything looks to be fine. I doubt this is a compression problem serious... The bike is way stronger then before when the carb was working properly.

 

[kelsorat]

Well I don't know about the reeds, as long as they aren't cracked or frayed that shouldn't be an issue

 

[crrod]

When you did the top end, did you remove the carb?

I just did the top end in my 99 CR125 Wed. evening. I didn't disturb the carb. I kicked it about 4 times after finishing the top end, then pulled the choke and it fired on the first kick. I was going to replace the reeds at the same time, but when I had the top end off I could see that it had carbon fiber reeds, and they looked good, so I left them alone.

I'm wondering if by removing the carb you have stuck something shut, or it needs adjustment.

I would start by making sure fuel flows out of the shut off vavle, this way you know it is getting to the carb. If that checkes out, with the fuel valve on, layt the bike over pretty far on the left side. This should allow fule to enter the carb and run out the over flow tube on to the ground. If this checks out, try starting it. If either one of those situations does not check out, correct either or both, as the case may be.

Good luck. BTW, my wiseco rebuild is running a bit quieter than the stock top end. I let mine idle for 5 minutes initally, with an occasional blip of the throttle. Then let it cool down good. After about an hour, I had time to take it for a spin, low throttle in 1st and 2nd. Did this for about 10 minutes. Next morning took the bike through all the gears down the gravel road about 2 miles, didn't get over half throttle, road around the yard in 1st through 3rd, about 20 minutes. That evening, took it down to the track in the pasture and after a few warm up laps, increased the throttle to approx. 2/3rds or so. Road it for about 30 minutes.

Just got it out this evening and put a pretty hard 2 hours on it, with an occasional break. Racing a friend on a YZ125. Lots of fun, and it took it like a champ, quite torquey now.

 

[crazy3rdgen]

You don't think any of the jets are clogged?

 

[crrod]

You don't think any of the jets are clogged?

Well, that is a possibility if you rotated the carb around when you removed it. I'd check the fuel flow first, as described. It is the easiest and quickest inital check, now tools or parts removal required.

 

[crazy3rdgen]

already did that earlier man.. I did the common sense crap lol, just don't know a lot about carbs may have to start studying the manual. But thought there was a prone problem in this situation. Could be many things is what I've figured out but it was coming out of the over flow some and the bowl was filled up, the floats were moving as well.

 

[crrod]

Have you tried starting it while holding the throttle wide open during the kick?

 

[crazy3rdgen]

tried it ..and.. the plug still bone dry with plenty of compression.

 

[crrod]

Don't know what to tell you. I'd just double check my carb settings. Make sure I fitted the throttle cable back on correctly. I'd actually hook up a compression tester and take a reading (won't be as high right now since the ring isn't seated).

If all else fails, clean the carburetor.

I’m still assuming you removed the carburetor, asked but not answered. BTW, fuel should run out of the overflow when leaned to the left side, not just a little bit.

 

[crazy3rdgen]

k I will make sure it's "running out of the over flow when tilted to the left" I meant it went out of the over flow a little when up right. And yes I pulled the motor , the carb has been off also. I know what bad compression feels like.. I felt it right before the re build and it's deff sounding better and is harder to kick.. but if you say soooo.

 

[crrod]

I'm not telling you to do it, I'm saying I would, and did. I like to know numbers, but that is just the way I am.

BTW, you actually pulled the motor to do the top end? Were you doing something else to the bike or motor?

 

[crrod]

I meant it went out of the over flow a little when up right.

Float set to high can cause this to happen. Shouldn't come out at all when upright.

 

[crazy3rdgen]

yeah it'll drip and i'll loose gas over time if I dont turn the fuel off.. Hmmm. I just learned something , thanks lol. Hopefully the manual covers how to adjust it.



Crrod i was cleaning everything up and wasnt sure if i was going to do the bottom end ... it wasnt too much of a pain but it is my first 125 so i was learning as i went.

 

[crrod]

Good luck in getting that fuel flow figured out. Bet it looks good since you cleaned it up so thorough.

 

[crrod]

BTW, this may seem silly, but, you did install the wiseco piston with the large hole in the side of the piston facing rearward (i.e. the intake) didn't you?

Did yours come pre drilled for the exhuast bridge? Mine did.

 

[crazy3rdgen]

there were holes in it that they showed in the manual if it doesnt have them to drill them.. it had them and the arrow on the piston faces foward. correct right?

 

[kelsorat]

Fuel flow is easy to diagnose. Still sounds like a compression issue. If the bike only starts with high revs then your pilot jet might be clogged, but you still better take a compression reading. Electrical issues are ruled out if you say your plug and reeds are dry. If you give me Wiseco P/N I could help you.

 

[kelsorat]

For example: p/n of 676m05400 is fine for a fresh motor, but if the previous owner bored out the sleeve to a 56.00 measurement, your bike will feel like it has good compression when you kick it, but it just ain't gonna work.

 

[crrod]

there were holes in it that they showed in the manual if it doesnt have them to drill them.. it had them and the arrow on the piston faces foward. correct right?

Correct, arrow on top of piston faces the exhaust port.

 

[crrod]

For example: p/n of 676m05400 is fine for a fresh motor, but if the previous owner bored out the sleeve to a 56.00 measurement, your bike will feel like it has good compression when you kick it, but it just ain't gonna work.

I think he would have noticed 2 mm worth of piston slop. That and the ring gap would have been enourmous.