Notices

Two-Stroke dirtbikes question

Thread Tools
 
Old 12-22-2017, 03:44 PM
  #1  
Gold Member
Gold Member
Thread Starter
 
seafordguy's Avatar
 
Join Date: Jun 2006
Location: Seaford, VA
Posts: 4,910
Received 771 Likes on 352 Posts
Default Two-Stroke dirtbikes question

so I bought my first two stroke - an RM 250 twostroke that was blown up, and rebuilt it just for fun.

Runs/idles good, but the power delivery is not consistent at all, particularly at partial throttle. Is this just the nature of the two stroke bikes or do I need to play with the jetting? It's basically slightly richer than stock jetting that I believe the previous owner richened up after he put the aftermarket exhaust on.

Carb is clean and freshly rebuilt, brand new throttle cable so it's not hanging up at all.

Any thoughts? Just got done with break-in so trying to figure it out
seafordguy is offline  
Old 12-22-2017, 04:02 PM
  #2  
Registered
iTrader: (1)
 
Join Date: Apr 2014
Posts: 2,264
Received 177 Likes on 114 Posts
Default

First thing to do with any 2 stroke is put a new plug in it. JMHO
GLENAMY 242SS is offline  
Old 12-22-2017, 04:03 PM
  #3  
Gold Member
Gold Member
Thread Starter
 
seafordguy's Avatar
 
Join Date: Jun 2006
Location: Seaford, VA
Posts: 4,910
Received 771 Likes on 352 Posts
Default

Brand new plug and wire. Gapped to OEM specs
seafordguy is offline  
Old 12-22-2017, 04:15 PM
  #4  
Registered
 
Join Date: Dec 2013
Location: houston texas
Posts: 483
Received 87 Likes on 33 Posts
Default

u got an old school motorcross bike
they we made for wide open throttle at high rpms
very doggish rolling throttle loading motor,,,,,,
when they get to the powerband u hold on,,,,lol
I still have my old honda cr250 sitting in my garage from when I used to motorcross
till I broke my collar bone on it ,,,,so sat it up in the corner for time out been there since

Last edited by johnmiffco; 12-22-2017 at 04:20 PM.
johnmiffco is offline  
Old 12-22-2017, 04:19 PM
  #5  
Registered
iTrader: (1)
 
Join Date: Apr 2014
Posts: 2,264
Received 177 Likes on 114 Posts
Default

Originally Posted by GLENAMY 242SS
First thing to do with any 2 stroke is put a new plug in it. JMHO
That is my opinion and I am sticking with it.

My first dirt bike was in 1960
GLENAMY 242SS is offline  
Old 12-22-2017, 04:21 PM
  #6  
SB
Registered
iTrader: (1)
 
Join Date: Nov 2004
Location: On A Dirt Floor
Posts: 13,543
Received 3,115 Likes on 1,402 Posts
Default

Could be you so you will need someone that nows dirt bikes to drive it and see if an issue or not.

2 strokes have an extremely narrow power band. Especially motocross engines. If you are in the wrong gear it ill be a dog.
Correct gear and you punch it...hold on and keep shifting

Pretend you have a 302cid smallblock with 270/280 at .050" cam and 102 LSA.

Last edited by SB; 12-22-2017 at 04:25 PM.
SB is offline  
Old 12-22-2017, 04:26 PM
  #7  
Registered
iTrader: (4)
 
Join Date: May 2009
Posts: 1,891
Received 460 Likes on 244 Posts
Default

DING ding ding ding ding ding diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii ing diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiing diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiing
brrrrgggggggghh brrrrrrrrggggggggggh diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiing diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiing diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiing

woo hoo
outonsafari is offline  
Old 12-22-2017, 04:40 PM
  #8  
Platinum Member
Platinum Member
iTrader: (6)
 
F-2 Speedy's Avatar
 
Join Date: May 2012
Location: Midwest & T-Rock
Posts: 10,416
Received 3,043 Likes on 1,355 Posts
Default

Originally Posted by SB
Could be you so you will need someone that nows dirt bikes to drive it and see if an issue or not.

2 strokes have an extremely narrow power band. Especially motocross engines. If you are in the wrong gear it ill be a dog.
Correct gear and you punch it...hold on and keep shifting

Pretend you have a 302cid smallblock with 270/280 at .050" cam and 102 LSA.
I like the 69 Z28 # matching 350 car.............
F-2 Speedy is offline  
Old 12-22-2017, 04:48 PM
  #9  
Gold Member
Gold Member
iTrader: (3)
 
vintage chromoly's Avatar
 
Join Date: Sep 2011
Location: cleveland ohio
Posts: 2,634
Received 12 Likes on 6 Posts
Default

I owned an RM250 for several years.
Mine ran just fine at part throttle. A 250 should pull well even if it's not in the ideal gear. Not like a 125 that will fall on its face if you're a gear to high.

I'd replace the reeds. Also, check to see if the power valve is carboned up.

Reeds are between the carb and jug.
power valve is in the jug in the exhaust port.
vintage chromoly is offline  
Old 12-22-2017, 04:49 PM
  #10  
SB
Registered
iTrader: (1)
 
Join Date: Nov 2004
Location: On A Dirt Floor
Posts: 13,543
Received 3,115 Likes on 1,402 Posts
Default

Originally Posted by outonsafari
DING ding ding ding ding ding diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii ing diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiing diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiing
brrrrgggggggghh brrrrrrrrggggggggggh diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiing diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiing diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiing

woo hoo
Haha ! Bringing out the crazy frog Axle huh ? The original :
https://www.youtube.com/watch?v=Vju2pyqXBLg&feature=youtu.be
SB is offline  


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.