250r timing

[trx450rlude]

Hello all. I am new here. I just got my first 250r (310 non powervalve motor), its an 86. I just have a couple of questions I would like some help with.

1. I think the timing is off. When I try to start it, it will sometimes backfire and almost blow the exhaust off the head...Is that timing? What else could cause this? Any tips on how to adjust the timing. I do have the manual.

I am fairly new to 2 strokes. I own some 4 strokes already and I'm really good with them....but I am still learning how to tune a 2 stroke. I have a 04 450r and a 03 z400 also.

here is a list of mods on the 250r just for refrence.
310 big bore
Laegar A-arms
Laegar swing arm
Durablue Axle
TCS remote rezzie front shocks
PEP remote rezzie rear shock..
There is alot more to list but Im to lazy at the moment....

thanks for any help guys.

[trx450rlude]

here is a couple of pics...needs some work, but I only paid 2000 for it, so I pretty happy.

[trx450rlude]

another

[matt250r21]

Take the side cover off by the shift lever, this is were the stator, pickup, and flywheel are. Unless you have an aftermarket ignition or an adjustable counter balancer bearing carrier (flywheel pickup bolts to this) stock 250r timming is not adjustable.

[wilkin250r]

I'll just echo what Matt said.

Unless you have something fancy, the timing isn't adjustable. If the flywheel is on the crank, and the flywheel key is in place, then the timing is set and correct.

For a definitive answer, pull off the left side cover (the side opposite the kickstarter). If you're careful, you won't even need to replace the gasket, but a little liquid gasket sealer wouldn't hurt upon reassembly.

Look at the pickup, make sure it's not bent or broken. Look for metal shavings or signs of damage.

[trx450rlude]

thanks guys I will check on that. But, if the timing is not off, then what else can cause this backfire issue. Is it because the the spark plug is not fireing correctly? or can it be the Jetting. I would think the jetting would have to be really rich to cause this type of back fire....any input on this...thanks alot guys...

[wilkin250r]

I don't know. That's what has me so stumped.

I suppose it's possible for the CDI to not be working correctly and firing at the wrong time. However, I've been around for a while, and this would be the first time I've ever heard of it. It's possible, but just not likely.

Post your carb size and jetting specs on here and somebody can give you advice whether you are in the ballpark or not.

It's difficult to diagnose over the internet, because I can't hear exactly what it's doing. So I could only give you the standard answers.

Start checking everything.

-New plug, clean filter.

-Inspect reeds

-Clean carb.

-Go through the electrical test procedure in the manual.

-compression test

-Leakdown test

You know, go through all the basics. The problem is somewhere, you've just got to go through the steps and find it.

[trx450rlude]

thanks, I will. I have only had it for 2 days and I have not had the time to check everything...Im not sure what size or what kind of carb it is yet, I havnt looked. I also will have to look to see what size jets are in it...I havnt got that far yet...thanks for your advice...:D

[hondardr4life]

Mine did that right after I got it and I let my one friend who doesn't have a clue how to ride a 2 stroke ride it in the woods. I put in a new plug, and it fired right back up. So I would try that if I was you

[dober250R]

Is this guy referring to the kickback of the kickstarter? Or is it more of a "pop" when he tries to start it?

[trx450rlude]

Originally posted by dober250R
Is this guy referring to the kickback of the kickstarter? Or is it more of a "pop" when he tries to start it?

no, Im talking about while its running, or when you are trying to start it...It backfire out of the exhaust where the exhaust goes into the head. It will nearly blow the exhaust right out of the head. It will also do it while running. I had it idleing and went to give it gas and it sounded like a cannon went off. I even seen what I think was part of the exhaust gasket come out where the exhaust mounts onto the head...

[DezSled]

get a flywheel puller and pull the flywheel. It maybe the woodruff key is not seated correctly making the flywheel timing off.

[beerock]

Originally posted by DezSled
get a flywheel puller and pull the flywheel. It maybe the woodruff key is not seated correctly making the flywheel timing off.

your almost right.

the only way the woodruff key could be not set is if it sheared OFF. I dealt with someone on the oldschool 250r forums and there was a major debate on it and I dealt with a bunch of BS back then, but it turned out my call about the woodruff key was right.

but im not to say i would be argued with now a days. annd cant positively say.

i woudl say change your plug first. but it sounds like the timing is really off. or bad wires... etc....

change the plug put fresh gas in it. if that dont work, then check the flywheel but you will need to buy a flywheel puller, but they are essential to have with this bike.....

[250rider1]

Ive been having the same problem for a long time now. Does yours do it after it gets hot and has ran for a while. It seems that once mine is hot it starts to backfire and it just dies and wont start for a long time. Could the cdi get hot and the timing gets knocked off? I cant come to a conclusion but ill check the flywheel like you guys are sayin. Let me know if you find what it is.

[trx450rlude]

Ok guys, I fixed the backfiring issue. It was just the plug. The old plug was black. I guess this means it is running rich. Does this mean the fuel mixture has too much oil in it, Or does it mean the main jet is to big?...Also It smokes a little more then it should from the exhaust. Does this mean the mixture is too rich, or is the main pilot to big?...thanks guys.

[wilkin250r]

Honestly, it could be either.

However, I've actually found it difficult to have TOO much oil. The manual says 20:1, (6.4 oz per gallon) but most people use a little less oil and go somewhere between 32:1 (4 oz per gallon) and 50:1. (2.56oz per gallon)

In reality, you shouldn't have any problems even going all the way to 12:1 (10.6 oz per gallon).

[trx450rlude]

thanks. So then what could cause the excessive smoking? If the pilot was to big would that make it smoke more, or would it just lack performance.....It seems to run really strong, no hesitation or cutting out..

[mrhyde]

These guys seem to know much more than me, however, when I got my r it smoked a lot. I changed the plug and set my idle and rode it hard. It no longer smokes excessively. I was told that the excess oil builds up in the silencer when it runs rich and will continue to smoke even when running good for a while. Good luck!

[matt250r21]

Two things that could cause it to smoke bad is a blown clutch side main bearing seal or the center case gasket leaking tranny oil into the crank. This will cause a whole lot of extra smoke. My Rs allways smoke a little on start up but after 1/2 lap there cleaned out.

[wilkin250r]

Like others have said, first and foremost you want to know exactly what the problem is before you go trying to fix it.

Does it ALWAYS smoke really bad? Then it's likely a bad seal or gasket, like Matt said.

However, if it smokes at startup, or after a prolonged period at idle or low RPM, it could be just a little oil buildup, and then stop smoking when it cleans itself out.