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Help me rebuild my 98 cr250 after top end! (picz)

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So as some of you know, I used to own this 1998 cr250 years ago and came back across her by the grace of god, so now it's mine again :lol: Yes, it trips me out.

Well it went through 2 immature "buy a cr250 just so I can say I own one" type of owners. Still had the same air filter and spark plug from 4 years before...However, bike runs great.

So far we have replaced:

-air filter

-spark plug

-all fluids (several times)

-complete throttle assembly tube/cable

-tires

-lots of aesthetic work done as well

Now, over the holidays we plan on:

-Brand new wiseco top end

-Reeds

-Pro circuit silencer to match my pro circuit expansion chamber

-Chain/sprockets

-New gaskets on everything we can get to

-Full chassis rebuild

Now, I was just wondering for this year model bike and everything I was wondering if you guys had any other suggestions on mods or things to replace while doing the top end? For this threads purposes I'm only really worried about getting the motor perfect. We are rebuilding the entire chassis/suspension also.

-Reeds...Not sure whether to do the Rad Valve or VF3? Have heard conflicting stories on both, or might just do Boyesen replacements and new gasket :)

-Chain/sprocket? No idea here. I've heard only get the steel sprocket for a bike as powerful as mine. Apparently these 250's and 450's eat up the aluminum ones?? I have found killer chain/sprocket deals on ebay the complete set with steel sprocket for $50! But should I stay away from those deals? Or should I stick with certain brand names?

Literally everything on this bike is all my work. The other guys just rode her and put her up wet :banghead: Sorry for the novel but just trying to get those few things sorted.

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Damn do I love these 90's CR's :cheers:

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i remember when rocky mountain atv was selling the RMA sprockets for like $17 or something. i bought up 1 since it was a cheaper off brand aluminum sprocket (pretty much in house rocky mountain atv i believe). freaking thing lasted forever. wish i would of bought up as many as i could. aluminum will wear quicker than steel, but my aluminum sprocket was still decent when i felt i wanted to replace it. aluminum isnt bad. proper adjustment and alignment go a long way.

chain: either the vt2 or the ert2 are my choice. one is a narrow oring which you will need if you want an oring chain, as most standard oring chains will rub your cases. this is something i can verify and have witnessed. the ERT2 is what i use and again, proper adjustment and alignment sure keeps this thing sitting nicely. no chain lubes here and adjustments are rarely needed.

if i can suggest something to replace during your top end i would say, crank seals and the right side collar that sits between the primacy gear and right crank bearing. your 98 will have quite a groove cut into it, you can be sure.

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i remember when rocky mountain atv was selling the RMA sprockets for like $17 or something. i bought up 1 since it was a cheaper off brand aluminum sprocket (pretty much in house rocky mountain atv i believe). freaking thing lasted forever. wish i would of bought up as many as i could. aluminum will wear quicker than steel, but my aluminum sprocket was still decent when i felt i wanted to replace it. aluminum isnt bad. proper adjustment and alignment go a long way.

chain: either the vt2 or the ert2 are my choice. one is a narrow oring which you will need if you want an oring chain, as most standard oring chains will rub your cases. this is something i can verify and have witnessed. the ERT2 is what i use and again, proper adjustment and alignment sure keeps this thing sitting nicely. no chain lubes here and adjustments are rarely needed.

if i can suggest something to replace during your top end i would say, crank seals and the right side collar that sits between the primacy gear and right crank bearing. your 98 will have quite a groove cut into it, you can be sure.

Thank you man now please explain is the ERT2 a "xring" chain? I am wondering the difference between o ring and the new x ring thing...Is it that you just don't have to lube a non o ring chain? Thanks for the info on the sprockets! That will help greatly. I'm sure the pros use aluminum for weight and also since they change them out regularly as well.

I think I got a bad idea of the aluminum ones because a guy with a 450 was eating them up and someone said aluminum is for 125's and smaller not for bigger bikes. In hindsight, I think that the guy just had some sort of alignment issue.

I'm not sure if we'll be doing the bottom end but I really really want to get to those crank seals AT LEAST... Thanks for your input!

:lol:

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Guys another issue I'm trying to sort is the terrible amount of vibration I am getting throughout this bike. Apparently the 97/98 were notorious for this due to the stiffened frames!

We were thinking about adding some sort of absorbing material to the motor mounts and on the footpegs, bars, etc...Any ideas past that?

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I have Renthal O-ring chain and Sunstar steel sprockets on my 02 cr250 no bs i have had them on my bike for 3 years now. i do woods riding get the bike packed with mud and track riding i have yet to adjust the chain and the sprockets still look brand new. Great combo i wont buy anything but from now on!

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I have Renthal O-ring chain and Sunstar steel sprockets on my 02 cr250 no bs i have had them on my bike for 3 years now. i do woods riding get the bike packed with mud and track riding i have yet to adjust the chain and the sprockets still look brand new. Great combo i wont buy anything but from now on!

Thank you for your input as I'll likely go with something I get good reviews from yall on here! Thanks! I want my sprocket black and I've noticed I can get a steel one in black I think so I should be good to go. I would just feel way better off knowing I got steel vs. aluminum.

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Guys another issue I'm trying to sort is the terrible amount of vibration I am getting throughout this bike. Apparently the 97/98 were notorious for this due to the stiffened frames!

We were thinking about adding some sort of absorbing material to the motor mounts and on the footpegs, bars, etc...Any ideas past that?

the cr's do vibrate, but if you truly are getting a horrible amount id look into that bottom end.

just to give you an idea, when i bought my 00, i dont know how many hours were on it, but it did have an original top end that was ready to pop (cracked on the intake side like high hour pistons get). i did the top end and then 7 hours later did the bottom end. i really couldnt feel any play in the main bearings from the flywheel side, but ill tell you what, when i split the cases and actually had some leverage on it, that thing had some real play to the point that i was glad i split the cases.

not saying that's what causing your vibration, but bad main bearings definitely show those symptoms.

the ert2 is a standard non oring chain. i personally do not even lubricate my chain. i clean it when it gets dirty and a little wd40 to keep it rust free.

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the cr's do vibrate, but if you truly are getting a horrible amount id look into that bottom end.

just to give you an idea, when i bought my 00, i dont know how many hours were on it, but it did have an original top end that was ready to pop (cracked on the intake side like high hour pistons get). i did the top end and then 7 hours later did the bottom end. i really couldnt feel any play in the main bearings from the flywheel side, but ill tell you what, when i split the cases and actually had some leverage on it, that thing had some real play to the point that i was glad i split the cases.

not saying that's what causing your vibration, but bad main bearings definitely show those symptoms.

the ert2 is a standard non oring chain. i personally do not even lubricate my chain. i clean it when it gets dirty and a little wd40 to keep it rust free.

Are you running the ert2 as well? Or you just saying you normally don't need to lube your o-ring chain?

Yea, the bottom end is something I just have that gut feeling about with this bike ALTHOUGH I think the vibration aspect is all in my buddies head. I don't think it's any more than normal when you add how old the bike is and even the little things like handle bars, old exhaust rubber mounts, etc. Keep in mind each of these parts are atleast 6-7 years old BUT I do feel like the crank and main could be replaced...I'm not sure what we'll do. Can't wait to see the looks of the inside of the cylinder and that will maybe tell me a bit more about what condition the rest of the motor is in.

All in all, the bike runs very smooth though other than this late mishap with the bike revving to the moon. It did it once a month or two ago on startup. We're positive the slide got stuck cuz' we removed it and put it back in and all was well, but then a couple weeks later at the track after a couple hours of riding it randomly just stood up, took off, did a backflip, and ripped the rear fender off while staying at full rev. I did not have a kill switch on the bike at the time :lol: but if anyone on here saw how bad off my throttle tube/ cable was they would highly suspect problems there. Not to mention my throttle cable was routed wrong. For the most part it was right, but it was going OVER my coolant and spark hoses, where as now it's correct where it runs UNDER.

I am too scared to actually ride the bike at the track for fear of it revving out again, but I feel pretty good about all new throttle hardware being the fix. I will give her some tests on trails this weekend to see what she does, hoping all goes well. We will do a leak down test at the time of top end rebuild (christmas) to verify FOR SURE.

No matter what though this spring this bike will be so right it'll be wrong. We'll even be replacing hardware with red/black anodized bolts. It will be one sharp looking bike both in looks and on the mechanical side.

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i run the ert2 and do not use any type of chain lube. i only try to keep her clean and rust free.

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The whole point of the non o-ring chains is you don't have to lube it, correct?

the theory/idea is that they have orings to keep lubricant "in" the chain at the points of wear.

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the theory/idea is that they have orings to keep lubricant "in" the chain at the points of wear.

Gotcha!

Tell me how my jetting changes sound to you guys. I am going straight out of the service manual.

I'm at sea level and basically above 60 degress F it's 175 main, 55 pilot, and 42 power jet with 2 turns out on the air screw.

Once it dips below 60 down to 30 degress F, I bump up to a 178 main and go to 1 and 3/4 turns on the air screw, so a quarter turn richer, and that's where I'm currently at THAT'S IT...

Obviously may be a tiny variation with the air screw but I just wanted to make sure that sounds okay to just only change the main. I know some people start at the top (main) and some at the bottom (pilot) but I just want to make sure that the bike is still not too lean...I've learned a ton about jetting but always still learning new stuff.

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