Yamaha turbo apex back firing

kylesrt · Nov 5, 2009

Hello guys.

First of all I have a 2006 Yamaha turbo'd apex boondocker turbo, Last year it blew the top lager diameter oil hose on the oil tank(cracked near tank and sprayed oil out. It threw a code low oil pressure. I shut it off towed it back. Let it sit in the trailer since.

This week I fixed the hose, purged the oil system, it still had the low oil pressure code flashing it would not start.

So I took it into the dealer, the verified the oil system had been purged properly, Cleared the code, They told me that it started and is running now, But that it was popping out of number one cylinder (clutch side) They did a leak test on all the cylinders, and number one would not hold at all, the other three pretty good.

I picked it up from the dealer and took the head off today valves look to be in pretty good shape, all cylinders look good, pistons looks good. I put alcohol in the intake ports in the number one cylinder and did not see any visible leaks, as well as the exhaust side on number one cylinder. Any idea's? Piston piston rings? I can turn the motor over by hand good, everything looks good to me, Any idea?????????? Thanks

letsgetrad · Nov 5, 2009

the temper is probably out of the rings.(they do not push outwards anymore)

Pastor · Nov 5, 2009

If your cylinder looks real good and the piston has no scratches then would it not be a possiblility the you are losing compression through the valves not seating properly?

0007 · Nov 5, 2009

Bummer
Somebody pulled a boner when they did the leak down, the question was being answered but it got missed
If you have a lot of leakage you check the breather, the intake and the exhaust to see where the leak is
This is a question that could have been answered in seconds during the test
Now you either put the head back on and do the test that should have been done or pull the pistons for visual inspection

What does the head gasket look like?, do you have black soot in your coolant?
Sounds weird that you put it away running and it developed a mechanical problem while in storage, there's some thing funny going on

kylesrt · Nov 6, 2009

I agree why did it develop a mechanical problem in the trailer, and why didn't they tell me its leaking out the bottom of the motor, middle or top, bottom woul be rings, middle head gasket, top valves. All the valves look really good look to be seating properly, no alcohol leaked out, On number one cylinder from me pulling the head, It had a little coolant sitting on the top of the piston, If the rings we're that shot wouldn't it leak past? Maybe, maybe not Just thought I'd throw that out there.

However I took the head to my really really good machine shop today and they are gonna pull the valves out and check them, seats etc, they are also going to check and adjust them if needed. The head gasket showed a little wear but It doesn't look like to me that its enough to cause a problem in only one cylinder. Any other idea's? I'll post some pictures that I took of the cylinder and pistons, hopefully they turn out ok.

Also what head gasket should I go with? I believe i currently has the stock one. No head shim. Stock one OK to run? I run 12 pounds of boost on half 91 and half 100.

Thanks for all your help.

kylesrt · Nov 6, 2009

Here's the pics

kylesrt · Nov 6, 2009

Not very good pictures Lol I know

chris79 · Nov 6, 2009

kylesrt said:
Not very good pictures Lol I know

Keep us posted,curious to see what you find out.

Pastor · Nov 6, 2009

What fuel are you running?

kylesrt · Nov 6, 2009

Maverick 91, and 100 VP.

0007 · Nov 6, 2009

I dont know about the boondocker kit's but I would have expected a head shim
Why dont you just do that now and then you can run pump gas

When you put the head back on do a leak down before you put the cams in
save yourself some questions and if it's leaking you will have less work to do
Actually, if I were you I would spray the gasket with some gasket adhesive and put the head back on so i could do a leak down again, just leave the cams on the bench
No i dont think coolant would gravity feed past the rings

I hate it when you have a machine in pieces and cant find mechanical problems, some guys think it's going to be obvious but often it's not

Make sure you check your valve clearance before you put the cover back on

kylesrt · Nov 6, 2009

Where can I buy a good head shim? What Head gasket procedure goes along with the head shim? I am going to have to buy a book on the apex to get all the torque specs and timing for it when I put it back together.

As I said before the machine shop has the head now, they are going to check the valves, valve seats, adjustments, etc. When I reassemble it I will spray the head gaskets with copper spray, as I have done with many 4 stroke 4 wheelers.

I also Hate it when You tear it apart hoping and thinking its gotta be a sticky valve, ruined cylinder, etc just to tear it apart and find really nothing obvious wrong, In some ways it's good you don't find a crappy valve, piston etc in other ways not so good because you have absolutely accomplished nothing lol. I do not have a leak tester, But I will try to find out to buy.

Thanks for everybody's help and input so far.

RX-1MT · Nov 6, 2009

I have a head shim and a already ground gear I would sell you all for 65.00 plus some shipping make sure the machine shop doesn't mix up your shims
keep us posted just a thought but was it just a bad plug or coil?

kylesrt · Nov 8, 2009

What head shim do you have? measurement wise? and whats the already ground gear? Something with the timing? Do you have a procedure on how to time the machine with the head shim? Also I did mention that don't mix up the valve adjustment pads, That would not be good. Now that I think about it I am starting to lean towards was number one spark plug bad, or is the coil bad, or something other than valves, pistons, rings, etc All i can do at this point is See what the machine shop says about the head install the head shim, new gaskets etc, Start it and see exactly what its doing, then go from there. How do you want me to pay for the head shim and gear? What head gasket do you use with your head shim? Thanks Kyle

RX-1MT · Nov 9, 2009

The head shim is from powder lites the gear is for the intake cam timing to put it back to stock timing without the shim I can get some pics of the marks just need to get back to the shop if you want them you can paypal me at nytromtx@hotmail.com use the stock head gasket just split it and use some copper coat when you put it back together
thanks mick

kylesrt · Nov 10, 2009

RX-1MT- I sent the money for the head shim and gear via papal this morning.

So With the already ground intake gear you time the motor as you would normally? No retarding the timing nor advancing it?

I also got my head back from the machine shop yesterday and talked to him about the sleds symptoms, told him I poured alcohol in both the intake and exhaust ports of the head, he said if they didn't leak that way they aren't leaking. And if it were him he would put the head back on bolt it all up and do a compression test myself then we'll go from there. I am starting to challenge the dealers integrity a little bit now that I think about it and talk around

When a motor looses oil pressure and has no oil, it doesn't take out set of pistons rings, or valves, generally the whole motor is toast, rods bearings, pistons, head, etc. That's what the low oil pressure sensor is suppose to do shut the motor off before catastrophic engine failure happens.

But maybe I am wrong, I'll keep everybody posted, I ordered a book from Yamaha on the apex to get torque specs timing specs etc.

RX-1MT · Nov 10, 2009

Thanks I will get it sent out to you ASAP

0007 · Nov 10, 2009

kylesrt said:
RX-1MT- I sent the money for the head shim and gear via papal this morning.

So With the already ground intake gear you time the motor as you would normally? No retarding the timing nor advancing it?

I also got my head back from the machine shop yesterday and talked to him about the sleds symptoms, told him I poured alcohol in both the intake and exhaust ports of the head, he said if they didn't leak that way they aren't leaking. And if it were him he would put the head back on bolt it all up and do a compression test myself then we'll go from there. I am starting to challenge the dealers integrity a little bit now that I think about it and talk around

When a motor looses oil pressure and has no oil, it doesn't take out set of pistons rings, or valves, generally the whole motor is toast, rods bearings, pistons, head, etc. That's what the low oil pressure sensor is suppose to do shut the motor off before catastrophic engine failure happens.

But maybe I am wrong, I'll keep everybody posted, I ordered a book from Yamaha on the apex to get torque specs timing specs etc.

Dont waste a minute on a compression test, it's a waste of time, if you find a cylinder with low comp you need to do a leak down anyway, find a tech who can do a leak down and pay him

if you run an engine with load and no oil pressure it will skid a rod bearing first often with no damage to piston or cam

kylesrt · Nov 11, 2009

I hate to say this but I think there leak test was B.S, the cams and cam towers show no signs of wear what so ever, neither does any of the pistons, head cylinder etc, I don't want to replace parts for fun that don't need to be changed.

I bought a leak down tester, I 'll leak check it myself.

After I picked up my head from the machine shop, I poured alcohol in the ports and this time it did leak out of a few intake ports Just to be sure again and i did find a few exhaust, and intake ports to be leaking some worse than others, some not so much, So I took it back to the machine shop and he is going to re cut the seats and check and adjust the valves.

Then I will bolt the head on and do a leak down test, with new head shim, head gaskets, valves etc, if it leaks then It more than likely has a piston or piston ring failure, I am now finding that hard to believe.

It ended last year with a code and wakes up this year with mechanical problems 007 mentioned previously. I am finding a lot of oil underneath the sled I am wondering if it is from pulling the head off or if there is a leak somewhere else, I'll keep digging.

Apex06 · Nov 14, 2009

So whats the scoop interested to hear what happen now.

Yamaha turbo apex back firing

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