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Author Topic: Runs like choked all the time  (Read 14915 times)

Offline PorP

Runs like choked all the time
« on: August 08, 2020, 08:36:27 PM »
Folks,  new here.  To summarize,  Tony Kellner (Barry hawks mechanic)  was my mechanic when I raced gnc /gncc on 450rs. I also had a 250r at this time and bought one of the 86 ported cylinders he had left over from hawk to run on my 87 250 with spacer for 265 cc's of monster power.  That lasted 2 hours before the counter balance bearings went out and broke a case. That was 2010. The quad sat as is without motor until this past month [fuel was drained from tank and carb).

2 months ago I bought the case i needed,  all new bearings and seals  for motor including water pump,  new stater, coil, countenance,  cdi, professionally rebuilt crank with hot rod and more.  I rebuilt the entire motor,  put that same rust-free top end on it and inspected the carb to make sure there was no gumming.

The thing started in 3 kicks, had a fuel leak from the petcock and it rev'ed high with  no throttle which I pulled the kill. I fixed the petcock and adjusted the slide to where I can hear it hit the bottom of the carb like I would on my 450r's.

Today now the tank is fixed,  i start it in 3 kicks.  Take it for 1/4 mile down the road and back..... it won't rev out, doesn't seem right at anything past an 1/8th throttle (always feels like the choke is on) . I change the cdi to make sure but it won't start cause the plug is so fouled. Put a new plug with the oem cdi and it is smoking like a chimney from the exhaust, blueish. Went back to the plug an hour later,  all the foul was completely dry,  didn't have the glisten of tyranny oil.

I'm running amsoil interceptor about 45:1, a PJ36 carb which is the same as i raced with for the PJ haters. Same jetting as when she dropped the counter balance.

I've got a good 4k sunk into this rebuild, which is already a full leager/pep 250r.  Before I sink more I am hoping this forum can help.

I am an avid mechanic,  I am not a pro.

That said,

I read right side crank seal can cause this,  the seal is definitely not damaged, can i have pounded it to far in?  Is not touching the bearing though?

Could it be the o rings in the carb dried up like they did in the petcock?  Note the carb is not leaking.

Did I drop the slide to far down?

Possibly something else?


Offline The norm

Re: Runs like choked all the time
« Reply #1 on: August 08, 2020, 09:09:46 PM »
Welcome to the forum bud.
First thing I would do is a leak down test.  That test will tell you if either crank seal is bad or if you have any air leaks in your engine. Then after that I would check your reeds, and all the ignition system . Download the manual off this site if you don't already have one.
Good luck with the resurrection!
Loren
1986 Trx250r-- Hybrid Engineering 391(Good bye super 310)
1986 Trx250r-- Hybrid Engineering  ported stock 86 cylinder
1986 Trx250r-- craigslist engine with unknown ported 89 cylinder.
1985 Atc250r-- Needs a lot of work (Super 310's new home)

Online 2ndmoto

Re: Runs like choked all the time
« Reply #2 on: August 08, 2020, 09:44:28 PM »
Sounds like air issue or a rich issue. Reeds good? Air filter clean? Air box lid on? What jetting you running now?

Offline PorP

Re: Runs like choked all the time
« Reply #3 on: August 09, 2020, 07:41:13 AM »
Thank you for the replies.

It is definitely rich, fouled the plug in 1/2 mile on the road. I checked the reeds while reassembling,  they are good.  Entire ignition is new,  I verified all components provided proper resistance per the shop manual.

I do not have a leak down tester. I'm going to pull the carb today but didn't change jetting from when it was running good.

Offline PorP

Re: Runs like choked all the time
« Reply #4 on: August 09, 2020, 07:46:41 AM »
also,  I run a twin air with no lid,  a full LRD adjustable exhaust.


One note i found odd, when i did the compression test the first time I got 155psi but forgot to hold WOT, I did it again WOT and got the same reading. I know 155 is not great and have rings on order but 155 should be plenty to run well.

Offline The norm

Re: Runs like choked all the time
« Reply #5 on: August 09, 2020, 12:06:07 PM »
So wet fouling the plug tells me that you are too rich,  but you were running this exact jetting before so that is odd. The compression is way low for sure. I built my leak tester from pvc and a gas test fitting all from home depot. Then I used a plug for the exhaust. I think I have $25 in it.
I wonder if maybe your float needs adjusted? I would have to check the manual for verification, but I believe it is 16mm from the carb body to the mold line in the float. You could be filling the carb with gas and it's getting into the cylinder.
Loren
1986 Trx250r-- Hybrid Engineering 391(Good bye super 310)
1986 Trx250r-- Hybrid Engineering  ported stock 86 cylinder
1986 Trx250r-- craigslist engine with unknown ported 89 cylinder.
1985 Atc250r-- Needs a lot of work (Super 310's new home)

Online 2ndmoto

Re: Runs like choked all the time
« Reply #6 on: August 09, 2020, 12:27:35 PM »
It's running rich, but why. Is it getting too much fuel? Not enough air? Something else is being burned with mix, like trans oil. Something blocking the exhaust. Poor combustion, poor spark.

155 psi on a race motor is low. Is your gauge good? The Schader valve and orings can go bad. If you gauge is good, you might have found your issue. poor compression will cause a poor burn.

I also highly suggest having/building a top end leak detector kit. They can be built pretty cheap and are a super useful tool to have.

Side note, is Kellner still around? Haven't heard anything about him since the hawk days.
« Last Edit: August 09, 2020, 12:42:23 PM by 2ndmoto »

Offline broken1

Re: Runs like choked all the time
« Reply #7 on: August 09, 2020, 12:30:48 PM »
16mm float level is correct but make sure you don't have the spring depressed in the spring loaded needle when you check the level.

Offline PorP

Re: Runs like choked all the time
« Reply #8 on: August 09, 2020, 01:12:45 PM »
I will make a leak tester....

I was just getting ready to check float height and then I broke the choke of in the carb when I was removing the bowl screws.... having a splendid weekend so far.

There is something definitely wrong with the floats though, they are sagging 24 or 25mm, way out of spec.

I run tame prox piston (9:1 if I remember right)  and stock head in it,  I don't like messing with race gas because I like going to hatfield mccoy.  I think 155psi is in spec for stock,  correct?  Thought the manual said 170 +/- 15. All that said,  am I really that far out at 155?

Offline PorP

Re: Runs like choked all the time
« Reply #9 on: August 09, 2020, 01:15:58 PM »
2ndmoto,

I'm not sure on Kellner,  maybe 2011 was the last time I used him?  Andy Lagzdins and I became good buddies,  his shop was in Baltimore (a lot closer for me) so I started using Andy when I needed help,  until he closed up shop and moved to cali.

Online 2ndmoto

Re: Runs like choked all the time
« Reply #10 on: August 09, 2020, 01:40:19 PM »
If you were jetted for a hi compression motor before and now have changed to low compression you will need to rejet.

Offline PorP

Re: Runs like choked all the time
« Reply #11 on: August 09, 2020, 02:20:29 PM »
Top end,  piston,  exhaust,  airbox/ filter and jetting are all the same exact parts from the last time it was running good.

The only thing changed is the spacer plate,  I didn't port match it cause I got too excited but I can't imagine that would cause an issue this big.

Offline broken1

Re: Runs like choked all the time
« Reply #12 on: August 09, 2020, 02:38:25 PM »
How thick is the spacer? Should be .190" if your just running an 85-86 piston on your long rod crank. A healthy fresh engine with a stock TRX head gasket will normally be 180psi +/-. Same exact engine with an ATC head gasket will be 200psi +/-. Both mine are 205psi with stock cylinders, wiseco 66.75mm pistons, 86 heads & ATC head gaskets. One is all 86 & the other is an 86 bottom with 89 cylinder & hotrods lr crank.

Offline The norm

Re: Runs like choked all the time
« Reply #13 on: August 09, 2020, 03:17:00 PM »
I would get the carburetor sorted out then see what happens.
1986 Trx250r-- Hybrid Engineering 391(Good bye super 310)
1986 Trx250r-- Hybrid Engineering  ported stock 86 cylinder
1986 Trx250r-- craigslist engine with unknown ported 89 cylinder.
1985 Atc250r-- Needs a lot of work (Super 310's new home)

Offline PorP

Re: Runs like choked all the time
« Reply #14 on: August 09, 2020, 03:27:53 PM »
How thick is the spacer? Should be .190" if your just running an 85-86 piston on your long rod crank. A healthy fresh engine with a stock TRX head gasket will normally be 180psi +/-. Same exact engine with an ATC head gasket will be 200psi +/-. Both mine are 205psi with stock cylinders, wiseco 66.75mm pistons, 86 heads & ATC head gaskets. One is all 86 & the other is an 86 bottom with 89 cylinder & hotrods lr crank.

It is 5 mil, 4.87 on my calipers and a trx gasket

I've not heard of the atc gasket thing?  Do you run 93 octane with that much psi?

At best if 180, I wouldn't expect 155 to make it so the bike sputters all the time and won't rev out, not optimal performance but I would still expect some perform.  Am I wrong?

 

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