2 stroke quad engine question
Thread Starter
|
Elder User
Joined: Jul 2004
Posts: 715
Likes: 0
From: Long island NY
2 stroke quad engine question
My yamaha blaster's engine wasnt running.. it would start if you pushed it and popped the clutch, but it barely ran at low speeds, and forget about idle'ing. wheny you kicked it over, it had prety low compression. I took the engine out prepareing to rebuild it, and i found one of the reeds was snapped off , heres a pic http://i31.photobucket.com/albums/c3...4/DSC00799.jpg
the clyinder and everything seems prety fresh, and I'm wondering, would a bad reed make the engine have low comrpression? It had about 40psi comression.
Im tryin not to spend a whole lot of money, so if i can skip the piston, rings, rebore, and just buy 35 dollar reed, it would be great.
the clyinder and everything seems prety fresh, and I'm wondering, would a bad reed make the engine have low comrpression? It had about 40psi comression.
Im tryin not to spend a whole lot of money, so if i can skip the piston, rings, rebore, and just buy 35 dollar reed, it would be great.
Elder User
Joined: Dec 2001
Posts: 800
Likes: 0
From: Ontario, canada
Do you know where the rest of the reed went?I had an outboard do this once and the reed was sucked through the engine damaging the piston, cylinder, crank and rod.
If bike ran fine and you have the broken part, then put in a new reed and see how it goes. If you cant find the reed, then a teardown and inspection is in order.
If bike ran fine and you have the broken part, then put in a new reed and see how it goes. If you cant find the reed, then a teardown and inspection is in order.
Hotshot
Joined: Jun 2003
Posts: 12,350
Likes: 4,384
From: SW VA
Well...since you need new reeds anyways, just replace it and see what she does. If it still has low compression...then I guess you need to check the rings, cylinder walls, and possibly the head gaskets.
At first, I thought it could be an ignition/CDI problem until you mentioned the low compression.
Please visit this website if you are still having trouble. This is a Yamaha Sport ATV site that will help you with everything you need.
http://www.bluetraxx.com/phpBB/index.php
At first, I thought it could be an ignition/CDI problem until you mentioned the low compression.
Please visit this website if you are still having trouble. This is a Yamaha Sport ATV site that will help you with everything you need.
http://www.bluetraxx.com/phpBB/index.php
Post Fiend
Joined: Mar 2004
Posts: 24,418
Likes: 3
From: San Francisco, Ca.
RyanMiller, Is that a Boyesen reed?
If it is, I think they were made not to damage the engine if it did fail, or use to back when I used them a long time ago.
Just like Fordzlla and ATC Crazy said, try replacing the reed valve.
I don't think it has anything to do with compression, but I'm not possitive.
Price out a Boyesen reed.
http://www.boyesen.com/
This also may give a little insight on two-stroke engines.
http://www.keveney.com/twostroke.html
Good luck.
If it is, I think they were made not to damage the engine if it did fail, or use to back when I used them a long time ago.
Just like Fordzlla and ATC Crazy said, try replacing the reed valve.
I don't think it has anything to do with compression, but I'm not possitive.
Price out a Boyesen reed.
http://www.boyesen.com/
This also may give a little insight on two-stroke engines.
http://www.keveney.com/twostroke.html
Good luck.
Thread Starter
|
Elder User
Joined: Jul 2004
Posts: 715
Likes: 0
From: Long island NY
not sure on what brand reeds they were, but I got the quad for 100 bucks, everything on it is fine except the engine. It wasnt running when I got it, but I was able to make it run for a bit. It ran fine, but it wouldnt idle.
I assume the broken reed was just digested by the engine and caused no problems because the cylinder and everything looks clean.
I think i'm goning to buy a larger piston/ring set and bore out the cylinder, being that I have the enigne out of the bike and half apart now.
I assume the broken reed was just digested by the engine and caused no problems because the cylinder and everything looks clean.
I think i'm goning to buy a larger piston/ring set and bore out the cylinder, being that I have the enigne out of the bike and half apart now.
Hotshot
Joined: May 2004
Posts: 12,170
Likes: 5
From: The hills of No. Calif.
40 psi is too low for a two-stroke engine. It's amazing that you could get it to run at all. I'd do rings at the bare minimum, but you're probably gonna be happier with the new piston/overbore job. Heck, you got the thing for a steal so you're bucks ahead even with that!
Trending Topics
Rub my Belly
Joined: Jan 2004
Posts: 3,093
Likes: 1
From: Lawrence, KS
Some of the 2 stroke engines have nickle plated cylinder walls. So a simple bore job can not be done. You have to buy new sleeves and in some cases new jugs also. Not sure if that is the case with yours but it has been that way with several of my dirtbikes.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Hotshot
Joined: Oct 2002
Posts: 18,488
Likes: 22
From: The Big, Oregon
The broken reed will cause a low compression reading, since rather than the piston's downward stroke puting pressure on the a/f mix in the crankcase and forcing it into the cylinder, it would just blow it back into the intake, making a partial vacuum. At higher rpms, it would act like a transfer port engine, with the velocity of the exhaust leaving sucking in enough a/f mix to keep it going.
Fleet Mechanic
Joined: Jan 2005
Posts: 1,413
Likes: 14
From: cape may county NJ
I had a blaster in for repair once and had the same problem broken reed low compression replaced the reed and it ran fine but since you have it apart go for the top end rebuild just check your crank for up and down play first there ruff on crank bearings.
after looking at your pic I think you are missing the reed stop backing plate but I could be wrong but most 2cycle reed motors have one It keeps the reed from opening to far and breaking off.
after looking at your pic I think you are missing the reed stop backing plate but I could be wrong but most 2cycle reed motors have one It keeps the reed from opening to far and breaking off.
Last edited by GlennFordx4; Jan 9, 2006 at 07:03 AM. Reason: add more info
Thread
Thread Starter
Forum
Replies
Last Post
earnhardtracer38
General NON-Automotive Conversation
3
May 2, 2007 09:50 AM
RyanMiller
General NON-Automotive Conversation
11
Apr 27, 2005 07:39 AM
shotgun_000
General NON-Automotive Conversation
36
Jun 25, 2003 10:22 AM