Author Topic: 1987 lt 250r engine with Lt 500r TM38 carb jetting questions (Read 1111 times)

Rem28ga · « **on:** January 02, 2014, 09:54:40 am »

I am finally ready to get the 1991 lt250r resto put back together. I was going to use my 1991 engine, but over the course of the holiday break I picked up a 1987 lt250r engine that has a newly sleeved, ported top end with wiseco piston with an o-ringed head and boyesen reed block. The engine was gone through and has less than ten hours on it. It came with the lt500r intake. I was planning on using a Pj38 carb that I had laying around but then opted for a 1987 Mikuni lt500r carb.

My question is, I am not sure where to start jetting this thing for the 250? I will be running a Dr Q pipe and silencer and live right at sea level. I want to pick up an assortment of pilots and main jets so once I start the process I can play with it a bit to see what works best. I just want to be in the ballpark when I start.

I am picking up my powder coated frame and parts early next week. I have all new bearings, bolts, odds and ends to get this bike put back together and hopefully get it out to the dunes end of January. Pretty excited to start putting it back together. Thanks in advance for your time.

Rem28ga · « **Reply #1 on:** January 03, 2014, 03:23:00 pm »

Hasn't anyone put a mikuni 38 on a lt250r? I am crazy for going down this path?

LT250RWV · « **Reply #2 on:** January 03, 2014, 03:42:38 pm »

Their a bunch out their hopefully they will chime in. I ship them hubs today. I going to pwk 38 with zilla intake setup and trx filter on my 91 . About same setup except im going to be running small reed setup.

Rem28ga · « **Reply #3 on:** January 03, 2014, 04:06:50 pm »

I have the PJ 38 as well, so if the TM38 doesn't work out, I will try the Keihin. I have some jetting specs to start with for the keihin so it might be fun to try them both and see what runs better. Thanks for the reply

Iceracer · « **Reply #4 on:** January 03, 2014, 04:14:01 pm »

I haven't used a 87 there slightly different but you should want @ 30 pilot a 389 Q6 or Q8 jet a stock 88+ needle and @ 440 main
On the needle you could be any where from 22.5-32 hard to say on a 87 depends on slide condition and engine setup.

Rem28ga · « **Reply #5 on:** January 03, 2014, 06:02:34 pm »

Thanks for the info. I am not sure what a 389 Q6 or Q8 jet is? Where would be a good source for a stock needle for an '88? When you refer to 22.5 to 32, are you referring to slide height? Thanks again I do appreciate your time and input.

LT250RWV · « **Reply #6 on:** January 03, 2014, 07:45:48 pm »

Quote from: Rem28ga on January 03, 2014, 06:02:34 pm

Thanks for the info. I am not sure what a 389 Q6 or Q8 jet is? Where would be a good source for a stock needle for an '88? When you refer to 22.5 to 32, are you referring to slide height? Thanks again I do appreciate your time and input.

22.5 to 32 is the pilot jet. Q6 or 8 jet needle the brass tube in the carb the needle slides in. The needle part number is 13383-43B00 can get it off the internet or take this part number to local shop and have them order it for you.

GrkGuy · « **Reply #7 on:** January 03, 2014, 09:04:39 pm »

or go through jason, honda east
he gives members a discount

Rem28ga · « **Reply #8 on:** January 03, 2014, 10:22:57 pm »

I just sent Jason an email through his info listed. What is his user name on here? How do you guys generally get a hold of him to place an order?
Thanks

Dezsled · « **Reply #9 on:** January 04, 2014, 01:21:52 am »

Yuzuha32 is Jason's screen name

GrkGuy · « **Reply #10 on:** January 04, 2014, 01:43:42 am »

its best to call the shop, i dont think he gets on here that much.

Rem28ga · « **Reply #11 on:** March 25, 2014, 05:33:50 pm »

I am in the middle of putting this all back together so tonight I figured I would swap out the pieces of my TM38 with the ones I got from Jason. How in THE hell do I get the keeper out from the inside of the slide so I can swap out the needle? If I remember correctly, the one in my zilla has two little screws holding the throttle cable in place. I do not see any such animal in this one. My PWK pushes in and 1/4 turn to pull it out. I don't want to force anything here, but am at a loss!

Gillio · « **Reply #12 on:** March 25, 2014, 05:49:03 pm »

Pull the spring out of the slide and and flip it upside down, the little plastic piece will come out and reveal the screws.

Dezsled · « **Reply #13 on:** March 25, 2014, 05:52:08 pm »

http://www.sudco.com/Diagrams323728/exptm.gif

Rem28ga · « **Reply #14 on:** March 25, 2014, 05:59:02 pm »

Sweet! Damn thing was stuck. I had pulled the spring aside before but did not flip completely over so the plastic piece would fall out. Thanks!

Next question: Does the needle jet just need to be tapped out? I am thinking it does. On some of my 4 strokes its just a slight press fit.

Thanks again

Gillio · « **Reply #15 on:** March 25, 2014, 06:11:14 pm »

Should just fall out after you remove the screws and cable retainer. You may have to apply a little pressure unless some one mashed a larger needle into it with out drilling the hole

Rem28ga · « **Reply #16 on:** March 25, 2014, 06:25:09 pm »

Thanks
I was referring to the tube that the jets screw in to. I got it out after I looked at the new one and pushed from the correct end

Mine was very stuck with old gas. It's out now, so now its time for a good cleaning. I can't wait to fire this thing up!

LT250RWV · « **Reply #17 on:** March 25, 2014, 07:05:28 pm »

The tube is called jet needle.

Gillio · « **Reply #18 on:** March 25, 2014, 07:22:31 pm »

Quote from: Rem28ga on March 25, 2014, 06:25:09 pm

Thanks
I was referring to the tube that the jets screw in to. I got it out after I looked at the new one and pushed from the correct end Mine was very stuck with old gas. It's out now, so now its time for a good cleaning. I can't wait to fire this thing up!

Gotcha. I misread that. Yeah the needle jets can require a little tapping.

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Author Topic: 1987 lt 250r engine with Lt 500r TM38 carb jetting questions (Read 1111 times)

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