200 xp losing rpms

[rattlin spot1]

I am posting this for a friend who is having problems with his 1987 xp 200 engine.The engine runs as it should until it gets to approx.4000 rpm's then it starts to surge or lose power.I beleive that its losing losing a cylinder when this happens.The engine has had the water pump,flywheel,sparkplugs and the electric fuelpump replaced.The manuel fuel pump and the vro were dissconnected several years ago.The carbs have been cleaned and kits installed.The engine has been to 2 shops and they cannot fix the problem.The last guy said that he has this problem before with engines of this year model and could not repair them.We have run it on a portable gas tank and the problem is still there.We have installed a timing light on each plug wire and the spark looks to be okay while the surging is present.The power packs have been changed out with known good ones and the problem is still there.The coils have been checked and show no problems.Nobody has been able to isolate the problem to one cylinder.Compression is 125 to 130lbs on all cylinders.If anyone can help we would be very grateful.Thanks.

 

[Dhadley]

Re: 200 xp losing rpms

Electric fuel pump? What electric fuel pump?<br /><br />That motor will run just fine. If that guy couldn't fix it, he just wasn't working on the right thing.<br /><br />Is your friend running with or without the airbox cover? What spark plugs?

 

[rattlin spot1]

Re: 200 xp losing rpms

Yes he is running the airbox cover.A previous owner had installed an electric pump.I know that he is running champion plugs i don't have the number but,i can find out.I know that he replaced them with the same # that he removed.He has spent a lot of money with one shop and still has the same problem that it had when they took the job.The other shops did not charge him because they did not correct the problem.I think because the rig is old the shops do not want to spend a lot of time on it.We also took a known good plug wire and tried it on all six cylinders one at a time.We are at wits end we've tried everything we know or that we've been told and the engine still does exactly the same as before.I know the engine can be repaired but,we don't know what to do next.Anyone that could help us we will be grateful to. THANKS.

 

[emdsapmgr]

Re: 200 xp losing rpms

Run the engine on a garden hose and put a timing light on each coil. See if they all fire and have strong, constant flashes. Possible you may have a bad stator. If you have a manual, there are a couple of simple electronic checks you can make which may/may not condem it.

 

[Dhadley]

Re: 200 xp losing rpms

Why did they change the flywheel? Are you sure they have an 86-87 flywheel and not an 88 & newer one?

 

[rattlin spot1]

Re: 200 xp losing rpms

A new stator was installed.The magnets on the flywheel had moved so the mechanic installed a "used" flywheel year model unknown.He spent almost $1200.00 with this guy and the engine ran no better or worse than before.This was with a major dealer in this area.We have had a light on each wire while in the water but,we can test again on the hose.Thanks.

 

[emdsapmgr]

Re: 200 xp losing rpms

What do the plugs look like? Does one look washed out, very clean, compared to the others?