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Author Topic: 87 lt250 not revving out  (Read 1073 times)

Offline MoparManiac

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87 lt250 not revving out
« on: November 14, 2021, 09:05:18 am »
Hey guys new to the forum, I've wanted a lt250r for years and finally got one, my problem is the top end power falls off quick, lower rpms are strong, starts 1st kick, idles perfect, great throttle response, engine has maybe 8 hours on it, I just got the bike a few days ago. Has k&n filter, fmf full exhaust. It seems to me like the power valve isn't opening. Choking the engine, it doesn't cut out or sputter just won't revv all the way out. Any help would be greatly appreciated.

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Offline turbowrenchhead

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Re: 87 lt250 not revving out
« Reply #1 on: November 14, 2021, 09:07:13 am »
I believe that your curve fails off 7000-7500 depending on your pipe

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1987 Yamaha Banshee (75 RWHP)
2002 Yamaha Blaster (25 RWHP)
1987 Suzuki LT250R (beginning restoration)

Offline Holeshot 500

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Re: 87 lt250 not revving out
« Reply #2 on: November 14, 2021, 02:13:54 pm »
Make sure you're running the same mix ratio as the previous owner.
Then I'd start with a new plug. Check that the air filter isn't over oiled and nobody left a rag in the airbox, check the silencer to make sure it doesn't have an obstruction inside.
Pull the nut off of the bottom of the carb floatbowl and make sure the main jet hasn't fallen out (trust me, seen it).
Welcome to the forum; let us know what you find out!
 

Offline turbowrenchhead

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Re: 87 lt250 not revving out
« Reply #3 on: November 14, 2021, 02:52:11 pm »
Check your compression

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1987 Yamaha Banshee (75 RWHP)
2002 Yamaha Blaster (25 RWHP)
1987 Suzuki LT250R (beginning restoration)

Offline MoparManiac

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Re: 87 lt250 not revving out
« Reply #4 on: November 14, 2021, 04:51:29 pm »
It definitely falls off to early, I'm pretty sure that the silencer needs repacked gonna do that tomorrow, it's still on the tank of gas that was in it when I got it, mixed with Klots 32:1, it don't seem to rich, no spooge out the silencer. It's got a pro design head also, I'm gonna check the plug tomorrow. I'll let you guys know what I find. I appreciate the quick responses, glad I found a forum still very active.

Offline Holeshot 500

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Re: 87 lt250 not revving out
« Reply #5 on: November 14, 2021, 05:11:55 pm »
There are a few of us still kickin' around here...  (Y)

See what I did there?- no electric starts...

Offline turbowrenchhead

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Re: 87 lt250 not revving out
« Reply #6 on: November 14, 2021, 06:14:43 pm »
It's really not that active compared to other forums. 

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1987 Yamaha Banshee (75 RWHP)
2002 Yamaha Blaster (25 RWHP)
1987 Suzuki LT250R (beginning restoration)

Offline MoparManiac

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Re: 87 lt250 not revving out
« Reply #7 on: November 17, 2021, 04:06:31 pm »
Ha I see what you did there! I love the kick start, I've got it running pretty good with a 260 main jet. But for the life of me I can't get the alignment right on this thing.

Offline Holeshot 500

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Re: 87 lt250 not revving out
« Reply #8 on: November 17, 2021, 09:52:54 pm »
Assuming nothing is bent or worn out?
If you search on here for 'camber mod' and bump-steer cure, you'll be a happy guy.
There is a guy on ebay that sells the camber shims. They are the same for 250/500s.

https://www.ebay.com/itm/303994913824?hash=item46c7824420:g:OIcAAOSwwiFfnV~p

Offline MoparManiac

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Re: 87 lt250 not revving out
« Reply #9 on: November 29, 2021, 03:51:56 pm »
Yeah I done some research and done the bumpsteer mod and that helped a great deal, one of my tierod mounts was bent so I got it straight wile doing the mod. I got it running pretty good also, it's still a little rich up top with a 250 main, I need to get some jets.

Offline Holeshot 500

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Re: 87 lt250 not revving out
« Reply #10 on: November 30, 2021, 08:29:57 am »
Glad to hear you're getting it dialed in.
Those camber shims will make a huge difference also.

Offline MoparManiac

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Re: 87 lt250 not revving out
« Reply #11 on: December 01, 2021, 04:33:16 pm »
I'm pretty happy with it other than the rear shock, it has pro action rezzy shocks on the front that are suprisingly good but Iit has an ltz400 shock on the rear and it's way to stiff, it's good on jumps but the ass end is bouncy as hell over rock n roots.

Offline turbowrenchhead

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Re: 87 lt250 not revving out
« Reply #12 on: December 01, 2021, 05:00:50 pm »
How much were your front shocks

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1987 Yamaha Banshee (75 RWHP)
2002 Yamaha Blaster (25 RWHP)
1987 Suzuki LT250R (beginning restoration)

Offline Holeshot 500

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Re: 87 lt250 not revving out
« Reply #13 on: December 01, 2021, 08:24:37 pm »
I'm pretty happy with it other than the rear shock, it has pro action rezzy shocks on the front that are suprisingly good but Iit has an ltz400 shock on the rear and it's way to stiff, it's good on jumps but the ass end is bouncy as hell over rock n roots.
You need to adjust the preload on the springs (fr and rr) so that the quad sits level with you on it. Have someone help you to eyeball it at first. After that you can adjust the compression and rebound on each end to get the ride you need.
Sounds like you could soften up the compression on the rear if the springs are close.

Offline MoparManiac

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Re: 87 lt250 not revving out
« Reply #14 on: December 02, 2021, 08:28:09 am »
Well it's an 87 and the previous owner put an ltz400 shock on it and it's just entirely to stiff even with preload all the way soft, I have a good 660 raptor rear shock I'm gonna get it revalced and resprung for my weight. From what I read they are a much better option for the rear than the z400 rear shock

Offline Holeshot 500

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Re: 87 lt250 not revving out
« Reply #15 on: December 02, 2021, 11:26:10 am »
Getting it set up for you is key! Good luck

 

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