250R question..please help

[swm250R]

Hey all! New to the board here. Been visiting 3WW for about a month now, everyone seems to know their stuff and it is a cool website. Love those restorations! Anyway, last week I picked up an '86 250R and have a few questions. The bike has a TwinAir dual stage airfilter and that seems to be the only modification. It has the stock exhuast pipe and stock gearing. Actually, it's all original equipment.....probably needs replacing. My question is how it runs on top end? In 1st, 2nd, 3rd, and 4th(5th and 6th I am not sure because the only road by my house is not long enough) all seem to level off extremely quick. 1st gear seems useless. As soon as the motor starts to rev into the powerband it seems to fall off, kind of like a rev limiter. low and midrange seem fine, it's when the powerband kicks in it is all over. It seems like it can't rev any higher and seems to slow down. Not sure if it is the characteristics of the pipe, gearing, or if it is a jetting issue? I replaced the plug with a champion RN2C but no change, so my original thoughts of a bad plug are incorrect. I had never riden a 250R until I bought this one so maybe its just the way it is. I have had two strokes in the past (125cc) and that is what I am comparing here. I just thought 1st and 2nd would wind out a little longer and harder. Any ideas would be appreciated. Thanks, steve

[hrc85250r]

ummm, clean the carb, and then ride it for a littlw while and check the plug...it sounds like you may be running too rich....does the power just not build anymore, like its hitting its max? or is it breaking up when its wound out??? if it just stops pulling you might be too lean...if it breaks up pretty bad it too rich....

[AZ250R]

Compression check IMO too. All the older trikes I've bought were well worn in the top end if ya know what I mean. :twisted:
However, ya can get through 1st & 2nd rather quickly most of the time even with a strong rebuilt engine. They are just too low, gearing wise, for flat out speed....

[TeamGeek6]

Yep on all that and - lose the Champion spark plug - worst junk on the market. Use only NGK or Autolite. I tried running Champs in street bikes and my van, they were total junk.

It should have enough grunt to surprise you. Probably carb. Check the spark in a dark place, it should jump white, if not, electrical troubles.

[slothminx]

check the compression and lose the champion spark plug - worst rubbish on the market. i use NGK. it shouldh have enough power to scare you.

[TimSr]

If its not missing or misfiring, or cutting out and just seems to top out at low RPM's it most likely has something do do with the airflow/exhaust system. This means check air filter, intake, and exhausst for any possible obstructions and also check the reeds. If nothing is found through there, its time to completely disassemble the carb, remove all jets and air screw and blow carb cleaner all the way through every orifice in the carb. Also pay special attention to the choke ciruit.

Ever worn cylinder Ive run across on a two stroke was characterized by difficulty starting when cold, appearance of running rich, loss of low end power, and running fine or even better on top end, so I doubt its your problem.

As for Champion plugs being junk, its the silliest nonsense Ive ever heard, and just plain bad information. I run them interchangeably with NGK, and have for years, and there is no distinguishable difference. The NGK's I aquired over the years as throw aways, and dont know how old they are but the Champions I bought new over 10 years ago, and they have recleaned and reused too many times to count. As I stated in another post, Ill match my stock TriZ with stock carb and Champion plugs against any trike out there, but for some reason, seems Im the only one showing up at the tracks with a few exceptions.

[willcamach]

ive only been into trikes for a year or so now but when i changed to a champion plug my bike totaly sucked ass. removed it put a fresh ngk and wham back to normal....and ive heard from many people that champions sucks. its our call but id stick with the ngk's

[TeamGeek6]

Tim, Champs have cheaper manufacturing processes that result in the internal resistor breaking open, leaky internal seals and a host of other problems. This goofs up the ignition system. What I posted about Champs was directly from an Autolite spark plug engineer. Its worse on multiple cylinder engines because one plug with an open internal resistor throws the cylinder out of balance. It wont show up so much on a single cyl.

[TeamGeek6]

As soon as the motor starts to rev into the powerband it seems to fall off, kind of like a rev limiter. low and midrange seem fine, it's when the powerband kicks in it is all over. It seems like it can't rev any higher and seems to slow down. Not sure if it is the characteristics of the pipe, gearing, or if it is a jetting issue? I replaced the plug with a champion RN2C but no change, so my original thoughts of a bad plug are incorrect.

yes, that probably rules out a bad plug, depending on the definition of "bad plug." A 2 stroke engine can very quickly (in a few seconds) foul a new plug if the carb is rich, or the spark is weak.

If it runs OK on low end, that pretty much rules out carb float. Its down to either main jetting or ignition (assuming a compression check is done before anything else)

Free test - remove the fuel tank and disconnect all the electrical connectors you can find, especially the CDi and ignition coil. Reconnect them and repeat several times. Then see how it runs.

My 250R wouldnt get out of its own way until I fixed a bad terminal on the CDi (ignition box).

If that doesnt show anything, run it at speeds that cause the problem as long as you think it will run safely, then kill the engine and look at the spark plug. See if its fouled. That would point to carb problems.

The reason the ignition is tied to high speed performance problems is that it tends to lose power as speed increases, very pronounced at 6000 RPM.

[OldSchoolin86]

Tim, Champs have cheaper manufacturing processes that result in the internal resistor breaking open, leaky internal seals and a host of other problems. This goofs up the ignition system. What I posted about Champs was directly from an Autolite spark plug engineer. Its worse on multiple cylinder engines because one plug with an open internal resistor throws the cylinder out of balance. It wont show up so much on a single cyl.
http://www.3wheeler.org/vb/images/smilies/doh.gifNo offence here TG6 but you really shouldn't trust bad mouthing from the competion.

[TimSr]

Tim, Champs have cheaper manufacturing processes that result in the internal resistor breaking open, leaky internal seals and a host of other problems. This goofs up the ignition system. What I posted about Champs was directly from an Autolite spark plug engineer. Its worse on multiple cylinder engines because one plug with an open internal resistor throws the cylinder out of balance. It wont show up so much on a single cyl.

About how many yeasr should it take before I start to see these problems, or do I just happen to have a half dozen oddball freak plugs that turned out good?

[RideRed250R]

LOL, most spark plugs are the same... except when you get into platium tips, twin tips and ALL THE OTHERS... i use NGK BR8es or BR7ES plugs.... the 7's are hotter plugs so make sure your carb and fuel are were they need to be... i run 91 or higher on the 7's ill run 89 on the 8's. I just have always done that for peace of mind. I also am going to ask.... whats your mix ratio? 32:1 is a great mixture 20:1 like the manuel said is WAY over the top... I say do this and it will make your bike run like a champ... I am almost sure i got this thing down...
Carb Rebuild Kit
BR8ES NGK plug
Soak your Air Filter in Gasoline... till all dirt rinses out... then service the filter with Air filter Oil....
ALL OFF THE ABOVE IS A MUST!!! try the next 2 if your still having problems
32:1 fuel mixture (use CR honda blend synthetic oil)
take your exhaust silencer off.... take a air compressor and put the hose in the stinger and let her rip... alot of yuck should fly out... (be out of garage)... then put it all back together and BAM you will be rippin around like crazy...
If it was compression that was the problem... you would have a HARD time starting the bike... and you didnt say that... so i think the above is your problem... PLEASE let us know if you get it all fixed
Adam

[swm250R]

Thanks for all the info guys. I will give them a try.