Need advice on upgrades for first gen 250R

[oldskool83]

200x front end, 85/86 front fender. extended swinger 2 inches, put 18's and 400ex hubs on it and offset rims. I have a extra set of 400ex hubs if needed. $50 shipped with fresh powder coated in red. renthal CR hi bend bars, YZ85 front master cylinder and ASV levers.

[loganm]

You should build a rack on the front fender and mount a CR85 engine to it and have 3 wheel drive

[rustyhondas]

Lol that looks like my house

[barnett468]

Ok, first of all, I am far from the foremost authority on this particular bike, however, a bike is a bike and they all must adhere to the same physics, so I threw together some stuff for you in addition to what has already been mentioned . I also posted where you can get many of the things . Some of the items have already been mentioned by others.

I addition to the shops I listed, I would also send a pm to atc007 and manbearpig and ask what they have . I think atc007 had a couple extended swingarms at one point and may have some of the other things on the list . manbearpig may also have some . The hubs posted by oldschool83 are a deal . I would buy them asap if you want 4 bolt wheels . I would also get a photo of the swingarm stoshu has and post it and people can let you know what they think . Not all swingarms are created equal and there are some I definitely wouldn't use.

There are a lot of options and they depend on how you will be riding the bike . Below is just one combo that will make it much more performance oriented but still far short of a full on race bike . It will make it noticeably harder to maneuver on tight trails but very few people ride trails like that frequently if ever . It will make it noticeably easier to slide and FAR less tippy in a turn, but it will make the ride a little more bumpy on some terrain . It will reduce rear end traction but that is easily compensated with tires and by simply sitting slightly farther rearward on the seat like maybe 1". It will reduce its tendency to wheelie . If you like to wheelie more than you like to slide, don't put a longer swing arm on it.


SWINGARM ............ 3" longer
HUBS .................... Used Honda 4 bolt X 110 mm spacing.
WHEELS ................ Used 9" ATC250R or used Douglass 9" or 10"
CYLINDER HEAD ..... Modify to increase compression.
CYLINDER .............. Used 84 ATC250R or mildly port yours.
EXHAUST ............... DG silencer.
CARB ..................... Used 83/84 250R 30 mm or Chinese Keihin or Mikuni 30 or 32.
SPARK PLUG ........... B9ES if compression is higher than 180 psi.
REAR SHOCK .......... Buy spring and revalve yours.
FRONT FORKS ........ 10w oil and heavier sprigs if necessary.
REAR TIRES ........... 20 x 11w x 9 or 20 X 11W X 10
FORK STOPS .......... Cut each one around 1/4".
AIR FILTER ............. Uni Filter.
AIR BOX LID .......... Drill 4 1" holes or remove it.
BRAKE HOSE .......... Steel braided.
BRAKE FLUID ......... Anything other than silicon base . Dot 4 is fine.
BOYSEN REEDS ...... PRO SERIES
STEERING ............. Steering damper if you ride high speeds.

I posted the specs below so you can easily see the differences between the bikes.

MODEL ................... WHEELBASE . WIDTH ..... FT WT DRY ..... RR WT DRY ...... CASTOR .. FT TRAIL . CARB

ATC 250R 81 & 82 .......... 47.1 ....... 42.3 ..... 117.0 . 38.7% . 185.0 . 63.5% ...... 40.0 ....... 1.80" .. 27 mm

3" swingarm, 2" spacers* 51.1 ........ 46.3 ..... 126.5 . 41.8% . 175.5 . 58.2% ...... 30.0 ...... 1.80" ...... ?

ATC 250R 83 ................. 49.6 ........ 42.1 ..... 117.0 . 39.9% .. 176.0 . 66.4% ..... 30.5 ...... 1.30" ... 30 mm

ATC250R 84 .................. 50.2 ........ 43.1 ....... SHOWS WET WEIGHT ONLY ......... 30.5 ...... 1.30" ... 30 mm

ATC 250R 85 ................. 51.0 ........ 44.1 ..... 117.0 . 40.2% .. 174.0 . 59.8% ..... 21.0* .... 1.45" ... 34 mm

ATC 250R 86 ................. 51.4 ........ 44.5 ..... 116.0 . 40.1% .. 173.0 . 59.9% ..... 21 30* ..... 1.49" ... 34 mm

TECATE . .84 & 85 ......... 50.4 ......... 43.9 ........... N/A ................ N/A ............... 24.0 ...... 1.57".... 32 mm
...
TECATE . .86 & 87 ......... 50.6 ......... 44.3 ........... N/A ................ N/A ............... 24.0 ...... 1.89" ... 34 mm

* The 4" wider axle will make the width the same as a pair of 2" wide wheel spacers . Some of the 4 x 110 hubs like the TRX300EX and TRZ400EX will increase the width by at least 1/2" per side . Many offset rims like the 85/86 ATC250R has will increase the width by around 1" per side.

* I think the 85 ATC250R castor number in the manual is for the steering head . I think both the 85 and 86 had staggered tripple trees and that the 30 number for the 86 is the castor of the forks themselves, ie. steering head 21 and forks 30.


X TIRES & WHEELS

In my experience, the best all around performance combo is a 10 diameter x 8.5 wide rim with a 20 diameter x 11 wide x 10 tire which just so happens to be exactly what the 86 Tecate has . This combo will make the ride noticeably bumpier over hard, rough terrain . If you don't want a bumpy ride and are willing to give up a little sliding ability, I would use a 9" or 8" rim with a similar diameter tire . The stock tire for your bike is 22 x 11 x 8 and the stock rim is 8 x 8.5.

With the 4 x 110 mm hubs, you can buy used 85/86 ATC250R rims from Ebay or buy new Douglas or possibly Mitchel rims.

4 plys on a tire are standard . 2 ply is useless . 6 ply is heavy but will reduce the chance for punctures over sharp rocks etc.

You can sometimes find deals on used wheels on Ebay but be careful because some are bent or dinged up.

If you ride on different terrains like hard pack dirt and moderately soft dirt and sand, this tire is one of many that would work well . Be careful when choosing a tire pattern because some will make it fairly hard to slide . If you ride on sand mainly, you should consider a paddle tire.


X REAR HUBS

You can fit both 9" and 10" rims to the 4 x 110 hubs that stoshu mentioned . You will may only find 8" rims for your stock hubs but I would not use stamped steel hubs for anything other than just cruising up and down the driveway . You can buy 4 x 110 factory hubs used on Ebay dirt cheap . Below is a partial list . New hubs will cost around $215 from Dura Blue . If you are on a budget by oldschools83 hubs.

Used 4 x 110 hubs for 9" & 10" rims

ATC200ES .84 . Stamped steel
ATC200X . .86-87 . Will increase width slightly
TRX250X ALL . Will increase width slightly
TRX300EX All . Will increase width slightly
TRX400EX All . Will increase width slightly
G Force aluminum........... Will increase width by 3"

DURA BLUE - Steel, standard offset p/n 201334 . 1" extended p/n 201334x . $224.00

http://durablue.com/prod_display/hub...r/10/0.php.htm


LONE STAR RACING - Billet aluminum 1" ? offset p/n 12-401.

http://lsracing.com/


X WHEEL SPACERS

These can be used in place of the extended axle if you are on a budget . They will cause a little more flex in a standard swing arm and standard axle but that's not a big deal unless you are a pro level racer.


X REAR AXLE . New $613.00

Dura Blue makes a standard length and one that is 2" wider on each end, however, it only works with the 82 disc brake setup . The 81 & 82 axles are different because of the different braes . If you use the extended axle, it will make it 1" longer on each side than the 85 & 86 ATC250R axle is . If you use ATC250R wheels, it will make the width from the outside of the tires around 1" wider than the 85 - 86 ATC250R.

DURA BLUE P/N 20-1115sp . Specify if you want standard length or extended.

http://durablue.com/prod_display/axles/5/0.php.htm


X SWINGARM

I would run a 3" extended one . This length is the most common for the 81 & 82, however, any extended swingarms for the foolers are very hard to find . . You might send stoshu a pm and have him send a photo of the one he has and you can post it and people can offer their opinions on it . Not all swingarms are made the same and there are some incredible pos arms out there . Used ones are virtually impossible to come buy . Dura Blue, Westcoast and PK are a few of the companies that made them and they are all good . You can also have one custom made at the shop below if he doesn't already make them.

The 81's had a rear drum brake . The late 81's may have had a disc but the 82's definitely had a disc . The swingarms are identical for both years with the exception of the brake bracket.

http://hreatv.com/productionparts.html


STEEL BRAIDED BRAKE LINES

These will provide a firmer lever feel . You can buy them separately or in a set . If you install a rear disc with an extended swingarm, you can get the longer line from them 4" longer rear, HOWEVER, the 4" longer rear is based on the 85/86 models, so verify the exact length you need.

http://motorcycleparts2u.com/galfer-...nes-mp2u082293


X CARBURETOR

It is VERY easy to over carburete a bike, especially that one . I would not use anything bigger than a 32 mm unless you do a lot of porting and run a lot of compression . A used 30 off an 83 or 84 ATC250R is decent upgrade or a new Mikuni VM30 or VM32 mm or a Keihin PE 30 or 32 mm . You can get a Chinese real Keihin carb on on Ebay but verify the size which will be stamped on the side because the sellers often state the incorrect size . You may need a different throttle cable.

USED 84 CARB WITH CABLE . $100.00 OR MAKE OFFER - The guy might take $70.00 or he can counter.

http://www.ebay.com/itm/498-1984-Hon...BV1Kkd&vxp=mtr


NEW MIKUNI 32-193 TWO STROKE CARB WITH RIGHT SIDE IDLE SCREW LIKE ORIG 250R CARB HAD

http://www.ebay.com/sch/i.html?_odkw...2-193&_sacat=0


X SPARK PLUG

If your kicking compression is around 180 or higher, I would try a B9ES plug . This is one step colder than the stock one which will reduce the potential for detonation.


X COMPRESSION AND HEAD GASKET

These engines probably have the lowest compression of any 2 stroke engine ever made by far . You MUST get the compression up if you want ANY significant increase in power . If you increase the compression enough, you will likely gain more power using a stock pipe with a straight thru silencer than you will if you leave the compression as is and put an aftermarket pipe on it . Increasing compression will increase power EVERYWHERE . Compression is your friend . If you increase compression, you will need to use premium gas instead of Kerosene.

Increasing compression is easy if you have the money . You can either buy an old DG ATC250R cylinder head OR have your head modified or possibly buy an 1984 ATC250R head . The 84 bike has much higher compression and a different p/n than the previous years so I can only guess that it has a much smaller combustion chamber, however, a true 84 head will be extremely hard to find . If the chamber is smaller, it will increase your static compression from an abysmal 6.6 to a much better 7.3, however, you benefit even more by running just a little bit more compression than that, unfortunately a real 84 head is hard to come buy and the Ebay ads are often incorrect . You can send Harry Klemm an email and ask him if he will modify your head or if he knows someone that will, however I did include the info for a couple other shops that can also do it.

This gets a bit complicated without doing some detailed calculations, however, my "guestimate" is that you can increase your compression to around 7.7 static/uncorrected with your stock port timing and not have detonation with premium gas and a straight thru silencer . If you have the cylinder ported a little, which would include raising the exhaust port at least .5 mm, you could run maybe 8.0 . The 84/85 Tecates have 8.3 . I don't know how much the DG heads will raise it.

There are two DG heads on Ebay right now for only $500.00 each, lol . They will also make your engine both run and look cooler .

STATIC COMPRESSION

81-82 ARC250R ...... 6.6:1
83 ..... ATC250R ......6.7:1
84 ...... ATC250R .... 7.3:1

84 ATC250R cyl head p/n 12200-964-670

BEAT DG HEAD . $500.00

http://www.ebay.com/itm/like/3613982...chn=ps&lpid=82


NICE DG HEAD . $500.00

http://www.ebay.com/itm/HONDA-ATC250...FWviqI&vxp=mtr


FOR CYLINDER HEAD COMPRESSION MODS . $125.00 - $250.00

The cheapest mod would be to have your head milled . This will require that a new squish band also be made but this is easy and could probably even be done by a high school machine shop if you of any . They should also have the piston that you plan to use because not all brands of pistons have the same dome shape and it is helpful to match the squish band shape to the piston fairly closely to reduce the potential for detonation.

HARRY KLEMM E MAIL - groupklemmail.com


RK TEK - http://www.2strokeheads.com/VintageMX.htm


DICKS RACING - https://www.dicksracing.com/motorcycle_performance


X CYLINDER MODIFICATION

Harry Klemm or Jason Hall for porting or buy an 84 ATC250R cylinder.


X PIPE & SILENCER

Bassani, Kerker Mugen, Cobra and Bills Pipes are just some of the companies that made pipes for those and they occasionally show up on Ebay . DG currently makes pipes for them . The DG silencer also fits at least the Mugen pipe and and I have also seen it on a stock pipe . You can buy just the silencer first to see if it gives you enough added power . If it doesn't, then buy a pipe . All the older pipes are extremely rare but you can periodically check Ebay for them.

Another option is a Bills Pipe . He may still have the jig to make them but a true cone pipe would be expensive . He may make formed pipes also though.

http://www.billspipes.com/

DG pipe p/n 01-2011, silencer p/n 20-2214.

http://dgperformance.com/dg-performa...odType=Exhaust

Cheaper on Ebay

http://www.ebay.com/sch/i.html?_odkw...-2011&_sacat=0

http://www.ebay.com/sch/i.html?_from...-2214&_sacat=0


X HIGH PERFORMANCE REEDS

Boysen Pro Reeds

http://www.boyesen.com/pro-series-reeds-20.html

You can also sometimes bend the metal reed stops open a little more, however, I wouldn't try this unless you know how because you could damage them.


X CYLINDER PORTING

A mild port job with the increase in compression will create a very noticeable increase in power . Porting the cylinder will cost a little power loss in the lower rpm range.

If you are on a budget but are handy with a dye grinder, you can raise the top of the exhaust port .5 mm and widen it 1 mm on each side then re-chamfer the edges slightly afterwards.

Remove 1.5 mm from the rear of the piston skirt . Use a large round file and file out the center leaving around 15 mm on each side untouched . You could actually put holes in the rear of the piston but I would try this minimum mod first to see if you get the level of power you want . You can always remove more later if you want but it's kinda hard to put it back.

Modify bottom of piston like the one on the right but don't remove as much material . The left is actually a stock Kawasaki 350 Big Horn rotary valve engine piston and the right is a forged Yamaha one Harry Klemm modified the skirt on for higher perf.

.................................................. .............


X SUSPENSION

A 3" extended swingarm will increase the rear travel by around 10% which isn't much . If you use the stock forks and shocks and determine it is too soft, you can get stiffer springs and get the rear revalved or just rebuilt at the site below.

You can make the front a little stiffer by using 10wt oil and adding a 3/4" long piece of pcv tubing to the top of the spring.

http://racetech.com/ProductSearch/3/...TC250R/1981-85


Here's the Works Performance shock that mentioned however, it needs rebuilding and the spring rate and valving may not be ideal for your app . Works can rebuild it or they can possibly make a new one for you.

http://www.ebay.com/itm/1981-1982-Ho...BWS7Jt&vxp=mtr

http://www.worksperformance.com/



All these tires are good for sliding.

Standard ITP Holeshot 4 ply 20x11x9 p/n 532032 . 20x11x10 p/n 532035 . $80.00

http://www.bikebandit.com/tires-tube...eshot-atv-tire

........


ITP Holeshot SR radial 4 ply 20x10x9 p/n 537203




MAXXIS RAZR MX ply ? These may be discontinued so check Ebay and ply rating . $132.00

http://www.ebay.ca/itm/MAXXIS-RAZR-M...-/371130587822

......


Kenda K300 Dominator 4 ply 20x11x9 and 20x11x10 . $83.00

http://www.bikebandit.com/tires-tube...nator-atv-tire

......


Sedona Bazooka 4 ply 20x11x9 and 20x11x10 . $68.00

http://www.bikebandit.com/tires-tube...untry-atv-tire


.

[atc300r]

Keep stock frontend they work well. Plus 3 swingarm is plenty rebuild rear shock or try and find a works. 4-6 inches wider is also plenty. You can still buy new DG full exhaust. If you can find a used one Bassani is realy good.Up grade your intake to the DG style. 34 mill carb .I think Mossbarger still makes and sells this style intake.

[Buck Snort]

Holy! Thanks! Very appreciated. Gives me lots of options. Your post will be saved into my favorites. Thanks again Barnett.

[Buck Snort]

Nice R! Pretty much what I want.

Keep stock frontend they work well. Plus 3 swingarm is plenty rebuild rear shock or try and find a works. 4-6 inches wider is also plenty. You can still buy new DG full exhaust. If you can find a used one Bassani is realy good.Up grade your intake to the DG style. 34 mill carb .I think Mossbarger still makes and sells this style intake.

[atc300r]

Here is what I believe to be a Bassani full exhaust first gen 250r . https://sandiego.craigslist.org/esd/snw/5471728334.html

[barnett468]

Unfortunately that pipe is not a cone pipe, plus there is no identification on it, therefore its value as a vintage/collector pipe is not very much imo . It is also definitely not a Klemm pipe.

[nicker71]

Here is what I believe to be a Bassani full exhaust first gen 250r . https://sandiego.craigslist.org/esd/snw/5471728334.html

Yep, looks like a bassani to me.

I have a pretty nice restored Bassani exhaust system for the first gen with chrome guard I'd sell. PM me if your interested.