Ok here we go.......Gotta newbie here. Last year I bought a 2005 Trailblazer 250 that I knew needed a set of rings. ( checked compression for a friend who had had enough and was not a mechanic) I had it bored 20 over and did the rest. Besides an off throttle knock that took me a week to figure out, (idle circuit too lean) my wife and daughter have been riding it problem free. I guessed at all the jetting and needle locations when I rebuilt the motor and carb. After tweeking a jet here and a needle location there I ended up with a 130 main and a hand drilled .035 idle with the needle in the middle slot. NOW my question. When I wined it up in neutral it comes down slow, like a lean condition, am I still to lean (or rich?) or is this normal for the Trailblazer? Sorry about the long post, just wanted to get you as much info as I could. Oh and I put a K&N on it with stock exhaust and air screw is 2 turn out. Putting in a new starter and drive gear this weekend so while I have it apart any input from you guys would be great. Thanks

 

Takes a 130 main jet and 40 pilot jet. Needle clip is normally set on the third position from the top by the factory. Drilling a 35 jet out a little may get it close to the 40. Playing around with the needle position may help on low to mid range. What most people overlook when they do a top end is the crank seals that could be sucking air. This can play havoc on adjusting the carb right along with the possibility it's the cause of the slow return to a normal idle. The one behind the drive clutch is usually the main culprit if it is a seal problem. You can do a 7-8 psi leak down test with soapy water to check for seepage at the head gasket,base gasket,intake manifold or even a case leak.Or you can take a chance on the seals first as they're cheap and replace them and see how it does.

 

Thanks for the response. OF Course! I wasn't even thinking of any kind of vacuum leak causing this issue! I just assumed the slow return was due to the centrifugal forces of the large clutch weight on the motor. I will look into replacing the seals when i get it apart this weekend. I'll try the leak down test first and see if the beer drinking mechanic messed up any of the head gaskets. (ahh me). As far as the jetting, I wasn't sure what the originals were, I just put in the post what i had written down. I find it odd that I wound up with the original jetting, seeing as it is .020 over and I installed a K&N? Thanks again and I'll be back........I think my daughters Predator 90 (Eton) needs rings! LOL

 

Just boring one and even installing a better breathing air filter may not always require a jetting change especially if it's still running the stock exhaust system.If you do get it running right and it's a crank seal problem ,just do a plug chop at speed. Pull the plug and see if the main jet needs to be bumped up if the plug color is on the whitish side and not a light to medium brown color.

 

Thanks again O.P.T. I had some time tonight so I have pulled the clutch side apart and the clutch off (previously mentioned starter project) and the crank seal on this side seams to be in good shape. I'll get the pull start off Friday night and check the other one. I'm going to replace them both anyway. Can I just pop them out with a seal puller? I'm going to leak test before and after. I also picked up an aftermarket exhaust REAL cheap on E-bay yesterday. Any idea where to start on my jetting?(2 or 3 sizes.......more??) I'll pick up a few more jets when I get the seals. Thanks for your time and I owe you a beer or two.

 

Seals just pop out easy with a seal puller. Jetting is just trial and error. Usually with a better flowing air filter along with an aftermarket exhaust some can do ok with stock jetting or bumping up a size or two. Rule of thumb is 10-15% above stock on jetting. I'd have a few jets on hand. Main thing is when plug chopping, the plug must be a light to medium tan and not whitish color.

 

I have one more question. After removing the pull start cover, I found some oil down by the starter gear and across the bottom of the case. This kinda makes me happy because now I know I have a leak and it can be fixed. I've pulled the flywheel, but how do I remove the stator? Do I have to disconnect the wires from the CDI and fish them all the way out or am I missing something here?

I've been reading a lot of posts on here and your a very busy man.(OPT) Thank you again for your time and helping us backyard ATV mechanics.

 

You can remove the stator plate assy and move it over the crank shaft out of the way to get to the seal. Just pull the stator harness grommet from the case if you need a little slack. Make sure there is a mark on the plate and engine case,if there isn't, make a mark to where you can line the plate back up.Dirt Cheap Yamaha & Polaris OEM Parts & Accessories – Cycle Parts Warehouse