new 310 cylinder on 250r and all it will do is bog???

[bushwacker51]

I replaced the 350 pv motor with a 310 cylinder in my 85 250r atc. The old kit had a plv ignition so replaced with used cdi new coil and ebay cdi box. Starts up but kicks back bad. All it does is bog like its getting to much fuel. I went up and down with jets might run a little better with bigger jets but not much. Tried another carb same thing bogs. Changed stator put a rickys stator in and a new honda coil and cap same thing just bogs. Hit the throttle it jut goes boooo boooo booo wont hardly rev. Its a new air stryker carb also. I am pulling my hair out any ideas ????????????????

[Dirtcrasher]

Gotta start with the basics...

You say you swapped carbs and ignitions, so I'd rule that out. Any air leaks??

Kick backs are often timing. IDK a ton about these ignition changes you've made, but they play a very big role.

Sometimes if you change too many things at once, it can be a nightmare, can you read the plug at all?

[bushwacker51]

[I have not checked air leaks I guess spray carb cleaner around the carb and intake ill try that andno the plug is wet but no color yes my next step is get a cdi box and try that I guess. Open for ideas

[bushwacker51]

I put stock cases back on and a new crankshaft and bearings rebuilt motor

[HondaRidr]

What kind of CDI did you put on it?

[bushwacker51]

I put one of those ebay cdis in . Kicks back like a sob. I ordered a used Honda cdi try that

[shortline10]

Their are no aftermarket CDI boxes for the 85 250r and if they claim to be they don’t work .
Lots of threads on this subject here on 3WW .

[HondaRidr]

I agree with shortline. I have never heard good things about any cdi other than OEM. Hopefully that will get it running good

[devilman]

Did you check the squish? Clearance between head and piston when at TDC? Not sure if that would cause kick back, but may cause the bogging.

[shortline10]

Kick back equals spark at the wrong time , so unless you have a sheared flywheel key that POS aftermarket CDI is the problem and hopefully it didn’t damage those fragile kicker gears .

[Curtis-Tecate3]

What Shortline said....
Kickback = Timing Issue that needs to be corrected.

[bushwacker51]

I was not trying to play clue or being an A-hole. The previous motor mounted in the 250r atc was a 350 pv motor. It had a pvl ignition on it. I I bought used cases and put new bearings and a new long stroke crankshaft in the new motor. I Bought a new 310 cylinder and high compression headand Rebuilt the motor. I bought a coil and cdi box off of ebay. I have since replaced the coil with a factory Honda coil and Rickies stator. It made no difference. I also checked the keyway and it is still okay. It does have the balancer that you can advance or retard the timing it is set on -0- I am going to take the pipe off and make sure its not plugged also going to put on the factory cdi when it arrives. Your right hope It did not screw up the kick starter gears. Never saw one kick back so bad before. It must be the cdi box thanks for all your help I will post what I find thanks Glenn O.

[bushwacker51]

I did not check the squish clearance if the cdi dosent work that could be next Glenn

[bushwacker51]

Okay got a used cdi box from ebay and that took care of the kick back problem starts so much easier but it is still bogging at low to mid rpm range. very difficult to get into the high rpm range. Have to down shift to raise rpms . When you get into higher rpms it snaps into the power band and then takes off. It has a new carb on it Took it apart and cleaned it out no difference. HELP PLEASE!!!

[floydechoes2000]

Is your exhaust clogged?

[shortline10]

How are your reeds ? The 250r is one of those motors that are highly sensitive when it comes to reeds .
You could also try going up or down some on the main jet to see if that helps .

[bushwacker51]

38mm air stryker. has no airbox just a metal attachment then air filter. has a 175 main jet tried 178 the needle clip is second form the top. not sure on the pilot.

[bushwacker51]

It is a cool head with high compression dome. I use race gas 112 octane. I have not checked the exhaust Ill do that sunday. I thought about replacing the reeds next. Never had one do this before. Ill stay with it until I figure it out. Thanks for all the ideas and help Glenn

[bushwacker51]

Okay pulled the pipe and blew compressed air through it then filled with gas shook it up emptied and nothing pipe was not plugged. I pulled carb apart has a cel needle and a number 50 piolet jet. Think I might try smaller piolet and needle see if that helps. Any thoughts please let me know thanks Glenn

[yaegerb]

If you still have your stock airbox and snorkel put it back on. Run a 48 pilot, needle 3rd clip from top and run a 164 pilot.

[bushwacker51]

the stock air box is long gone. I can try the 48 pilot and a smaller main jet is the cel needle okay or do I need to lean that out also?

[yaegerb]

I think you are fat across the board. You can try raising the needle clip to the first clip and see if that helps before you start messing with the Jets. Air boxes are a critical feature of an engine. They are essentially wave resonators and are a certain intake track length for the fuel and air mixture. I would recommend finding a set up and putting your air box and intake tract back on.

[bushwacker51]

I have messed around with the needle clip no luck ordered new reeds and smaller pilot jet and needle going to try and see if that works. I think you are right its to fat thanks for all the advice Glenn

[bkm]

Close up the plug gap to about .018 and run a new plug.

[bushwacker51]

Close up the plug gap to about .018 and run a new plug.

I will try that thanks Glenn

[bkm]

I will try that thanks GlennAny updates?

[bushwacker51]

Sorry been out of town for a week. Ordered some smaller main and pilot jets from ebay and they got lost in the mail. The seller said he is going to reship them also bought new reeds will put them on this weekend I will give an update when the jets come in. Glenn O.

[bushwacker51]

Okay I figured it out and I am embarrassed to say what I discovered. I feel like a moron. The motor Had low compression. I pulled the head and discovered that I put the piston in backwards. Screwed up the cylinder and will need a new sleeve. Okay I told on myself. I really dont know how that happened. I know the arrow goes to the exhaust. What the hell guess I am just getting old. Thanks for all the help Glenn O.

[El Camexican]

Ouch, that sucks. Can you get a sleeve off the shelve, or do you need to get one made?

[bkm]

Don't feel bad. I rebuilt my 250r top end years ago and forgot to put coolant in the radiator. It ran for about 20 minutes before I seized it.

[bushwacker51]

Yes a shop in Wichita, Kansas said they can get a sleeve for like 200 dollars. I feel like the biggest loser in the world but crap happens. I did not want to post my screw up but thought just in case someone else runs into the same problems maybe this post will help. Glenn O.

[El Camexican]

Sh*t happens and we learn from it. Someone has to keep the scrap metal dealers in business, might as well be us.:beer

[Snazzy93]

It may still be a timing issue. Is the ignition all stock at this point?

Also what compression ratio are you currently at? 2 strokes in my experience, are alot fussier with compression changes.

[Snazzy93]

Pardon me, didn't realize there were 3 pages lol..... glad you at least figured it out. It happens to anybody. And the ones who say they haven't done something like this themselves are lying.

[bushwacker51]

Thats okay Snazzy thanks for trying to help. It liked to drove me crazy and I should have ran a compression check from the start but we all know it cant be bad compression when we have a new piston and rings lol. Your right everyone screws up it sucks but we are all human Glenn O.

[ironchop]

Yes a shop in Wichita, Kansas said they can get a sleeve for like 200 dollars.....

F.A.S.T. Racing?

If so, I've had good results with them myself



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