Ultima class 250

thomas mitchell
Edited Date/Time 1/26/2012 8:41pm
What is the best bike for the class between 84 suzuki, 84 yamaha, or 83 honda. That includes doing the basics like 82 head on RM and fixing all forks with springs and emulators. I have an 84 yz and wish it had the hit of my 85 yz but if you read my previous post on 84 yz I am torn about putting an 85 cylinder and head on the 84 since it is going the wrong way as far as years. Going backwards like the 84 RM to 82 head swap doesn't bother me. Never rode the other 2 bikes, have a feeling they are both better. The CR has the drama with the corrosion though.
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CamP
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CamP 11/3/2010 1:38pm
11/3/2010 1:38pm
The RM is the best of the bunch.
evomx244
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evomx244 11/3/2010 2:26pm
11/3/2010 2:26pm
I've raced a 1983 RM 250 and 1983 CR 250 in AHRMA. It's close but I think the 83 CR 250 was a better overall.
thomas mitchell 11/3/2010 4:51pm
11/3/2010 4:51pm
I know the 82 is the one to collect. The 83 can be turned into 82 motor wise and comes with 43 mm forks but just strictly from a racing aspect is the 84 RM better than the 82-83 ?
Bill163
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Bill163 11/3/2010 8:39pm
11/3/2010 8:39pm Edited Date/Time 11/3/2010 8:40pm
thomas mitchell wrote:
What is the best bike for the class between 84 suzuki, 84 yamaha, or 83 honda. That includes doing the basics like 82 head on RM...
What is the best bike for the class between 84 suzuki, 84 yamaha, or 83 honda. That includes doing the basics like 82 head on RM and fixing all forks with springs and emulators. I have an 84 yz and wish it had the hit of my 85 yz but if you read my previous post on 84 yz I am torn about putting an 85 cylinder and head on the 84 since it is going the wrong way as far as years. Going backwards like the 84 RM to 82 head swap doesn't bother me. Never rode the other 2 bikes, have a feeling they are both better. The CR has the drama with the corrosion though.
Your splitting hairs nothing wrong with running a newer top end on the 84 people run all types of new-old stuff all the time in vintage and post vintage don't worry about the AHRMA police.



Stay away from the CR the clutch cover can be troublesome but there are fixes.The real issue is replacement transmission gears there is a very short supply otherwise a good bike.



CamP is correct go with the RM but don't worry about the head exchange you can do a head mod for less than the hassle of finding a 82 head and new studs.That was a good engine and any engine parts from 83-85 will work only the head and cylinder from the 82 will work 83-85 has a different transmission and cases internally.



Just upgrade the suspension springs F&R run race tech fork emulators and replace the shock seal head and bumper from race tech and hard anodize the shock body.Also upgrade the pegs.



Hope this helps

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thomas mitchell 11/4/2010 6:37am
11/4/2010 6:37am
Bill 163 your post did help and thanks. I picked the Ultima era of bikes because it was the time frame that I so enjoyed motocross.

Besides the corrosion issues on the CR you pointed out the gear problem. So I would agree good bike but finding parts would become an issue.

Am listening to everyone's advice on the Suzuki.

As far as my 84 yz. I think I need to quit worry about the AHRMA police and run the 85 top end on it. Like I said I have a 85 yz 250 that I ride more than the 84. I really like its power and could not imagine a power plant I would like more. Handling wise the 2 bikes are the same and even the front disc on the 85 vs. DLS on the 84 feel about the same to me. I like the bikes but don't really like messing with the power valve and it does exhibit the dreaded Yamahop. That I am not too crazy about. I am sure I can bring the forks up to snuff with the Race Tech stuff but the rear I don't know. Will an Ohlins be able to overcome a mediocre linkage design ? It would be an expensive trial.


I think the best thing is just to go out and find a RM (while keeping my YZs) and see what fits my 42 year old body the best.
koolstrike 11/4/2010 9:31am
11/4/2010 9:31am
I would not be too concerned with 1983 CR250 transmission parts. From looking online it appears that almost every piece is still available from Honda.
If the part is not available from Honda it is very easy to find a used lower end on ebay or a salvage yard. I have not found transmission to be a "high wear" item. Either they are working or they break and from my experience they don't break often.

The 1983 water pump cover can be replaced with a cover from a 1981 CR250 which is made from aluminum. That creates a permanent fix for that bike.

A 1983 CR250 is a GREAT bike. As is the 1983 RM250, almost every RM250 part is still available OEM from Suzuki.
The 1984 RM250's had a change in the rear shock which many riders do not like. Suzuki lowered the rear shock in the frame which created handling problems with the bike. As a vintage rider you may not notice.

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