What do I need to do to fix the engine in my 90 Phazer?

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snow4me

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Nov 29, 2007
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Livonia, MI
Hi all, I just got a 90 Phazer II from a friend of mine for free. The clutch side piston has a burn hole right in the center of it. The head looks fine but the jug will probably need to be honed at least. What should I do to fix this for my son to use as his first real trail sled? I don't know what caused the problem yet but I assume the carb on that side is the culprit. The sled has 5000 miles on it and is in really good condition. What needs to be done to the engine, does it have to come out? Could I just have the jugs bored and put new pistons in it? What brand pistons, Wiesco? Sorry for the rambling, lots of questions.

Thanks, Daryl
 
MY opinion would be to use OEM parts for starters. Being that there is a burn down involved, I would pull it right apart. Now is a good opportunity to go through everything being that this is a "new to you" sled. Have a good look at everything.

My$.02.
 
I agree on tearing it down. A melt down could be due to a crank seal. Also you cannot get all the contamination out without tearing it down. Oem pistons will work fine but, so will Wisecos. Which ever is easier/cheaper to buy. I personally run Wisecos because they are less likely to fail. I like the price of the OEMs better. Oem is still available std. and .020. Wisecos are available in std. and 5 oversizes.
 
I would tear it down and go all thru it. It's an easy engine to work on. I would use Kimpex pistons (and have) before I would ever consider Wiseco. It will be a fun worthwhile project.
 
Yes you need to tear into it, BUT . . .

I always try to figure out what caused the problem before tearing it apart. You may find that the problem is external to the engine, and after rebuilding the engine may still be there. I would suspect clogged jets or an air leak.
 
Also this is a fan cooled engine. A hole in the top of the is clearly a lean condition but, while it is apart You need to make sure the fan bearings are in good shape and put a new belt in it.
 
pressure test it before you tear it apart to rule out crank seals if it is not leaking thru seals then just do top end and carbs
 
Sorry I haven't posted back to this topic, I appreciate all the suggestions and advice. I have been so busy I haven't had the time to mess with the phazer yet. I do have the heads off but that's about it. I have located a new set of wiseco's for $90 with the pins that are .020 over but I hate to buy them yet without knowing how far over the cyl's need to be to clean up. I really hate to pull the whole thing down since I have never done a lower end in a small engine like this. Where can I get a manual to read on rebuilding this? Thanks, I promise to check back right away.

EDIT: Just looked in a parts book I have and it shows the stock bore at 72 millimeters and the wiseco pistons are apparently offered in 0.25mm, 0.5mm, 1mm, and 1.50mm oversize. Is this correct tha this bore and pistons are measured in millimeters? So if I brought the jugs to the machine shop I would ask if he can bore and hone them to a final size of 72.25 millimeters? And then use the 0.25mm over pistons?
 
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