Question about Boyesen Suzuki Rm125 Rad Valve Rm 125 89-91

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Backfiring - popping full throttle start up and idle great

Fresh rebuild piston rings top end it just wont top out full throttle

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2004 Ram 2500 starts, low idle 400 rpm and stalls, any ideas?

With out see it running on a scanner. Maybe the IAC or throttle body. Does it have any codes. Did you erase codes after rebuild? Any time I do a rebuild on engines and transmission, the codes have to to erased. Other wise you are trying to run a new part on old PCM codes. Codes have to be erased.

Dec 13, 2016 | 2004 Dodge Ram 2500

1 Answer

Why is my 250 recon knocking when has a fresh piston and rings with only 2 hours of riding it?

the question is did you remove the ridge at the top of the bore before you put the new piston and rings in. If you didn't then the knock could be from a broken top ring or broken ring land under top ring
all cylinders wear up to where the top ring stops and when new pistons and rings are fitted this wear point hits the ring as with a new piston the ring now travels further up the cylinder

May 13, 2015 | Motorcycles

3 Answers

I have a 1980 rm125 it does not start it just back fires

usually a 2 stroke will chuff/backfire out of the exhaust if it low on compression, did you put the rings in the right grooves and up the right way and is the piston in the right way around as there is a front and back ,the ring pegs are supposed to face the inlet side of the barrel.

Feb 15, 2015 | GAS Motorcycles

1 Answer

Husqvarna 128LD backfires through carb when increasing throttle.

Possibly an ignition module issue, on the advance settings. It could be sparking before the piston closes the fuel port from the carb

Apr 05, 2012 | Husqvarna Garden

1 Answer

My 1982 Honda 200e starting missing about a month ago, sometimes it will backfire, it runs but poorly, plug was black. Had the fuel changed, carb cleaned and still the same!!

With any naturally aspirated motor, aside from timing, your fuel/air mixture is crucial at part-throttle as well as at wide-open throttle and off-idle. Sounds like your running too lean on the top end and too rich at part-throttle and off-idle. You should focus on either preliminary adjustments to your carbs; rebuilding or replacing them. You may also consider re-metering and re-jetting your carbs.

Jun 07, 2011 | 1974 Honda CB 200

1 Answer

My yz 125 made a loud popping noise when i tried to kick it up now it wont start any suggestions

They can do this from time to time. What can happen is the expansion chamber gets pumped with fuel vapor and then can be ignited, causing a large backfire. I hate to attempt to answer your question with a question, but how old is the piston and ring? A ring won't last very long in a 125. For racing, it's changed every race. For joy riding 15-20 hours of run time and it's time for a ring at least. Weak compression can make it impossible to start. If you have perfect compression the cause for the non-start could be something as simple as a burned up or fouled spark plug.

Start by re-ringing the motor (you can do this for about $25 inside of 2 hours time). Clean the carb out, clean the air filter, fill the tank with fresh fuel and replace the spark plug (NGK B9ES - from Autozone for $1.89). If the bottom end of the engine is good, the above steps should get it fired up - providing your ignition system is good, and based on the apparent backfire, I would say you have spark.


May 17, 2011 | 2003 Yamaha YZ 125

1 Answer

2002 polaris scram. 90 cc. all new top end and new carb. Come 2 me with no compression, found rings stuck to piston and jug scratched up. Like i said new top end and carb. starts great and idles great,But...

First question since i am assuming it was just sitting around for some time if i am correct you need to pull the carb remove the float bowl and components if everything was done correctly with your rebuild the likely problem is your carb is gummed up remove everything in the carb low speed jet etc. soak everything in sea foam fuel cleaner overnight and hopefully you have some compressed air and blow out that low speed jet and passage way pay close attention that you have see fluid coming from the other end and check the jet make sure it is unclogged hold it up to the light.

Nov 06, 2017 | Polaris ATV

1 Answer

I have a 1979 Yamaha GT80 that I recently got running, but very poorly. I have rebuilt the carburetor and decoked the top end. It is hard to start and once started, will not idle. When giving it throttle...

did you check the clearances between piston & bore it sounds very much like its time for a rebore & oversize piston that is a top end rebuild rather than just a clean up

Feb 23, 2010 | 1972 Yamaha XS2

1 Answer

Bought a 2002 Rm125 about 2 months ago, with a fresh top end....First ride was great with impressive power throughout. About two weeks later I noticed that it was missing some about half throttle , and...

My first thought is low compression... which leads to a few questions...
What fuel to oil ratio have you used?
What do you mean by 'fresh top end'? To me a fresh top end includes piston and rings and cylinder bore, gaskets and crank seals. Anything less on a 2-stroke is an incomplete job and usually leads to premature failure.
Have you followed break-in procedure on your fresh top end? Double check the head bolt torque.

Do a compression check first then go from there.

Dec 28, 2009 | Suzuki RM 125 Motorcycles

2 Answers

Was driving my o6 kx 85 . was at full speed and it cut out and refused to start and when i try to start it , it would backfire i think its getting a spark but no starting . does anyone know what the...

sounds like you might need to rebuild the top end and check the rod bearings remember when doing a top end always change piston and rings and use new base and head gasket

Apr 13, 2009 | 2001 KTM MXC 250

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