2 Stroke 1988 CR250R Wont start / Wet Plug

[Stringer]

Thanks

I decided to stay with black pipes. I don't have the tools/materials to put a real shine on that pipe. Plus I've polished the exhaust pipe before on a DR650SE, and it was a bad idea. The pipe got hotter than a coated pipe, everything would stick to it and melt including flesh, and the rust is always an issue. I quickly painted it black and never looked back.

Well I decided to go ahead and use the self etching primer on the pipe as well, time will tell if this was a good idea I guess. Then I scuffed it up with steel wool and hit it with a few coats of VHT. Hope it holds up well. Looks light in color due to flash.


I painted the subframe the same way, with duplicolor GM Torch Red.


That should keep the small rust issues I was having at bay. And my boots came in! No more irreparable foot damage trying to kick start this beast!


And then my craigslist find. Matching helmet, gloves, goggles, and jersey for $40! Used once lol. Must have been a fun ride.



Still waiting on that cylinder. Hopefully tomorrow ...

 

[Stringer]

Today the paint is dry so I mounted up the subframe and airbox assembly. I must say the paint is a pretty decent match. Much better looking than rust! I got my airbox so clean you can eat out of it, and got the new UNI filter in there with fresh UNI filter oil and maxima waterproof grease as a sealant. I also installed an acerbis mud flap since my old one was toast. It was advertised to fit my bike specifically, but it was universal and required drilling, trimming, filing, etc.




I was also experimenting with polishing using steel wool. Was getting great results on the rear shock canister but stopped because it was leaving behind steel wool particles and I want to button up the engine first. In this last pic you can see the two paints side by side, so you can see what the Duplicolor Torch Red looks like next to my existing paint (center top).

 

[Mihylo33]

Good build thread

 

[Stringer]

Thanks. Feels good to post here because nobody in this household shares my enthusiasm lol

This morning I had a weak moment, and ordered two new radiators, a half gallon of evans waterless powersport coolant, and a moose racing 25mm radiator hose protector all for $130 shipped. This with the new red silicone hoses on the way should complete my cooling system makeover!

 

[Stringer]

Finally after a week in USPS custody, I have received my used eBay cylinder and head today (and powervalve assemblies, covers, tons of hardware, gaskets, etc)! Obviously I'm no expert, but this looks to be in good condition. I hit them up with some engine degreaser, then on to a bucket of hot water, soft plastic brush, and dawn soap. A real good rinse, then wiped dry and wd40 applied to steel parts and wiped again.



Immediately brought cylinder to brother in law's house and had it spec'd. We both measured, and came up with the same figure using his tools. He had a snap (something) set, and used some kind of caliper to guage the snap tools. The caliper was supposed to be of very high quality, it had a dial but read only in inches so I did the conversion. The reading we both got was 2.615" which converts to 66.421mm. So what piston set should I get? Right now I have no clue what size piston to order. I am so anxious to order so hopefully, that will be the last thing I need (fingers crossed!)

 

[Stringer]

Oh forgot to add! He gave me this contraption to hone the bore, but honestly it looks scary and I'm afraid I might screw something up!

Im not sure I trust myself attaching it to a drill and sticking it down the bore?!?! Is there an easier way??

Thanks!!

 

[SRAD97750]

Oh forgot to add! He gave me this contraption to hone the bore, but honestly it looks scary and I'm afraid I might screw something up!
View attachment 23413
Im not sure I trust myself attaching it to a drill and sticking it down the bore?!?! Is there an easier way??

Thanks!!

That's the hone I use on my STEEL 2Ts. You have a Steel cylinder as well.
I can see the original crosshatch in the cylinder in picture #1... No need to hone unless you feel something with your fingernail.
Looks good to go!

http://www.ebay.com/itm/1986-1987-1...Parts_Accessories&hash=item19ec8ac3a0&vxp=mtr
This piston is 66.36 which leave you a cylinder/piston clearance of 0.06mm or 0.002" which is perfect.

You don't have to buy Namura, there are a ton of other manufacturers if you look around. I prefer Wiseco over any other piston manufacturer.
Namura is cheap and I have yet to have a single issue when running proper premix ratio. Others will tell you different. This is just the first kit I found on ebay.
-BIG DAN

 

[Stringer]

Ok Thanks BIGDAN! Do you think I should at least hit the cylinder with steel wool or anything or just leave it? Well since I have everything apart and all I guess I'd rather go with a wiseco if it's a better piston. Though I only see them in 66.40 size. Would this be too tight?

I also see 66.36 in a Pro-X brand which I believe to be Japanese OEM under a different label. Is the 0.06mm or 0.002" ideal? Should I go this route? Thanks!

 

[SRAD97750]

Ok Thanks BIGDAN! Do you think I should at least hit the cylinder with steel wool or anything or just leave it? Well since I have everything apart and all I guess I'd rather go with a wiseco if it's a better piston. Though I only see them in 66.40 size. Would this be too tight?

I am not saying it's a better piston. Just my preference.
I am willing to bet the Wiseco 'piston size' is the bore measurement, for easy reference. The piston will probably measure 66.36-38, and fit a 66.40+ bore. Ask them to send you the actual dimension.

You can steel wool and 2T oil wipe the cylinders if you want. Or you can hone it for experience if you want. Either way, it does not look bad.
-BIG DAN

 

[Stringer]

Well I have not contacted wiseco but all I have is their 66.40 advertised spec. Im guessing if this is true, it's little on the tight side. If not true, they need to advertise as such.

Namura is probably just fine but possibly on the lower end of the quality scale judging by price? Im thinking PRO-X at this point. I guess before I order I just want to be certain of the right size piston kit to get. I know you said a 66.36, but it looks like they have the surrounding sizes covered too. Are you still thinking 66.36? If so I'll order this size. Thanks!

Also looks like the failed head gasket that was on this bike was K&S brand. Turns out I bout the same entire engine gasket kit. And upon removal of gasket from eBay cylinder it looked to be of higher quality compared to this K&S. Even though I have the whole engine gasket kit, I think I will order perhaps what seems to be a better head gasket from eBay, maybe OEM on this one?

 

[Stringer]

I really need to order this piston and keep things moving along. My wife wants her screened porch back.

I was reading an article about piston sizing, written by Eric Gorr. From what I understand he is somewhat of an expert on these things. I even remember seeing a 1988 CR250R for sale on eBay and one of it's selling points was the engine was rebuilt by this guy. I've seen his name a lot anyway. He is basicly saying the same as BIGDAN, that 0.002" is ideal. Well a quick conversion shows 0.002" = 0.0508mm. My cylinder measurement is 66.421mm so I guess I'll take 66.421 - 0.0508 = 66.3702. So I guess a PRO-X piston in size A3/66.37mm is in order here?? Also need another head gasket, should I go OEM on this?? Thanks!

http://www.off-road.gr/article25.html

 

[Stringer]

From what im able to gather this should be the kit for me, and at a great price.

http://www.ebay.com/itm/Pro-X-Pisto...Parts_Accessories&hash=item35cebadc4f&vxp=mtr

I noticed it does not come with a needle bearing. Should I buy one separate?

 

[SRAD97750]

From what im able to gather this should be the kit for me, and at a great price.

http://www.ebay.com/itm/Pro-X-Pisto...Parts_Accessories&hash=item35cebadc4f&vxp=mtr

I noticed it does not come with a needle bearing. Should I buy one separate?

Yes, you'll need to find one elsewhere. I don't know why, but that is typical of piston kits to exclude the pin bearing.

 

[Stringer]

Yes, you'll need to find one elsewhere. I don't know why, but that is typical of piston kits to exclude the pin bearing.

Ok thanks! I just ordered the 66.37mm PRO-X piston kit, and a new Shindy wrist pin needle bearing for $86 shipped.

I guess I'll just use this new coated steel K&S head gasket I have. Its $20 for an OEM one. Im sure this one will be fine?

 

[PALMER84ONE]

Namura is junk, I would not use one. Just pulled the motor apart on a YZ with less than 10 hours and the cylinder needs a run down. Not my rebuild, the shitty shop called Inside Line Racing! Live and learn, have 17 hours on my first rebuild on my sons bike, no problems.