Low compression 1 cylinder

[Kathy]

Goodness don't know how with all the posting i do i missed this!
It was a little hard to find good parts for me. Lots of junk yard calls and ended up finding nicer stuff.
I would recommend boring over a small bit with the scoring.
The engine is so simple to work on that it's basically fun!
New pistons all the way through with an overbore and a slightly cleaned up head would be awesome.
I had polished the inside of my heads to reduce detonation and then milled it down slightly.
I had also replaced the cranks with hotrods cranks which you can source from island racing but i found some used and in good condition.
All in all i replaced in pieces one and a half motor worth of parts. I DID witness a few things from sbt that i didn't like such as cheap gaskets and washers that were on oem and not on sbt pistons.
If the shop can do it all for that price then you are golden because parts is one of the hardest things.

I had bought the exciter for 2k and put 2k into parts.

I wish I only spent 2K on it.. with all the little this and that so far including sending the cylinders out for work I think I'm in it for just over 6k now.. ugh.. :/

 

[Bruce]

Which tach did you switch into? I saw someone went to the Faria ones.

I switched all the gauges to Faria versions that were on closeout at the time. I will dig up some pictures.

I believe this is the same part number that I used but with a little different look http://greatlakesskipper.com/faria-thc052b-custom-black-silver-inboard-outboard-7000-rpm-boat-tachometer-gauge-w-hour-meter?gclid=CL21-_nzlM4CFQqPaQodITIPmg

This thread documents my install but most of the pictures are missing.

 

[M@__]

Sounds like you've got this all figured out. All I'll add is get another set of hands when you drop the top-end on the pistons. It's tricky getting all the rings compressed at the same time as supporting the jugs. Otherwise, it's fun. Ohh yeah, one more thing, use mikuni gaskets for the carbs and use yamaha gaskets for the rest.

 

[Kathy]

Sounds like you've got this all figured out. All I'll add is get another set of hands when you drop the top-end on the pistons. It's tricky getting all the rings compressed at the same time as supporting the jugs. Otherwise, it's fun. Ohh yeah, one more thing, use mikuni gaskets for the carbs and use yamaha gaskets for the rest.

Kewl thanks for the tip.. I was going to ask if anyone had experience using Mikuni vs non.. I was going to opt for Mikuni ones even though they're more $$

 

[Kathy]

So and update to the Mikuni rebuild kits - most places are out of stock on these things.. I ended up getting some rebuild kits from guys at Action Power Sports in AZ. He was telling me that the diaphragm is manufactured by the same people who supply Mikuni. I guess we'll see how things go - he seemed to pretty confident in this kit.
I got my plug wires back from rebuild by JetSki Solutions - the turnaround was super fast.
New parts and pieces every week - can't wait for those cylinders to get back here.

 

[Tyler]

I also have low compression in one cylinder, but figured I'd throw in my two cents on gauges, lol. I went with Teleflex 63474P tachs with hour meters. Also picked up the matching speedo 63475P and fuel 63477P gauges. Have had them 2 1/2 years and put over 100 hours on them with no issues. They also light up. Product pictures online make the inner ring look blue, but it's actually black. I'll post a pic when I get home.

 

[AZDANSX230HO]

So and update to the Mikuni rebuild kits - most places are out of stock on these things.. I ended up getting some rebuild kits from guys at Action Power Sports in AZ. He was telling me that the diaphragm is manufactured by the same people who supply Mikuni. I guess we'll see how things go - he seemed to pretty confident in this kit.
I got my plug wires back from rebuild by JetSki Solutions - the turnaround was super fast.
New parts and pieces every week - can't wait for those cylinders to get back here. View attachment 43615

Steve from Action Power Sports knows his stuff when it comes to anything with a jet ski motor, he can be a bit brash on the phone, but does top notch work.

 

[4x15mph]

@Kathy, plugs look great and glad to hear that full bore is able to help out. Keep us posted since everyone is always asking where to get help with rebuilds.

Do you run the boat hard? Have you considered installing the groupk fuel/air separator? It helps prevent lean conditions since it is essentially a fuel pump that draws out the air. I don't know that this is your problem given this was 1 cylinder but it can always contribute. It also makes starting the boat after sitting a quick turn of the key.

I also have to add that while it is apart, at least clean out the exhaust chamber on that bad engine. I would guarantee that it is not completely clean and not having the proper cooling I suspect has caused many people problems that were never diagnosed correctly... cooling system.

I like the oil pump as long as the oil lines are secured and maintained. With premix you introduce new issues (smoke, having to mix at the right ratio, dirty carb = less oil to engine, )

 

[ISLANDRACING]

I was going to ask if anyone had experience using Mikuni vs non.. I was going to opt for Mikuni ones even though they're more $$

...After rebuilding racks in the thousands, we would NEVER use anything but the GENUINE MIKUNI kits! We had plenty of kits in stock.

 

[M@__]

...After rebuilding racks in the thousands, we would NEVER use anything but the GENUINE MIKUNI kits! We had plenty of kits in stock.

Epic post. For sure what I've heard, but that's straight from the source code of the Matrix.

 

[Kathy]

@Kathy, plugs look great and glad to hear that full bore is able to help out. Keep us posted since everyone is always asking where to get help with rebuilds.

Do you run the boat hard? Have you considered installing the groupk fuel/air separator? It helps prevent lean conditions since it is essentially a fuel pump that draws out the air. I don't know that this is your problem given this was 1 cylinder but it can always contribute. It also makes starting the boat after sitting a quick turn of the key.

I also have to add that while it is apart, at least clean out the exhaust chamber on that bad engine. I would guarantee that it is not completely clean and not having the proper cooling I suspect has caused many people problems that were never diagnosed correctly... cooling system.

I like the oil pump as long as the oil lines are secured and maintained. With premix you introduce new issues (smoke, having to mix at the right ratio, dirty carb = less oil to engine, )

The cylinders are on the way back now and I should be getting them on Friday this week - took longer than I expected though.
The only one time I ran the boat after I got the new cleanout plugs I did get on it pretty good - I guess I have a lead hand too...
I did get the groupk part right before I decided to check that compression and pulled the motor apart so all the new stuff I had lined up to get the boat in proper running order is now getting installed, and I didn't like how long it took to get the boat started after sitting - too much wear and tear on the starter and a drain on the battery. My stand up is a pain to start up too but that's a whole other project..
The other thing that happened was the boat would stall out sometimes during turn or heavy wake - I figured it was the rear hatch switches. I replaced the hatch lock which helped some but then one motor would die so I do think it's the switch itself so after putting in a "shim" under the hatch at where they make contact with the lid it seemed to help. We'll have to see for sure after everything gets put back together with all the new parts and the groupk part goes in - I read its supposed to help with the fuel sloshing issue also, though I could be completely confusing that with something else..
Is there a post on cleaning out the exhaust chamber? I guess I could look it up but being lazy at the moment.
I'm replacing all the oil lines and getting things ready for putting things back together - running out of boating time here. I hope I have enough time to break the motor in before having to pull it out for the winter.
SAGA continues...

 

[Kathy]

...After rebuilding racks in the thousands, we would NEVER use anything but the GENUINE MIKUNI kits! We had plenty of kits in stock.

I wasn't for sure on the kits to order, I wanted to call and ask but the web page says something about not calling the number about order related questions.

 

[4x15mph]

Kathy, sorry that i never wrote up the process. There is the exhaust chamber and after you take it off there is an inner baffle that has 3 holes. They get clogged easily

Part #33 below. I had to replace 32, 33, 34, and 37 (rubber ring that was melted...).

I would always use mikuni parts for the carbs based on what I read and based on a personal experience. Rebuilt a carb because of what was a suspect, non Mikuni kit.

 

[Kathy]

Kathy, sorry that i never wrote up the process. There is the exhaust chamber and after you take it off there is an inner baffle that has 3 holes. They get clogged easily

Part #33 below. I had to replace 32, 33, 34, and 37 (rubber ring that was melted...).

I would always use mikuni parts for the carbs based on what I read and based on a personal experience. Rebuilt a carb because of what was a suspect, non Mikuni kit.

View attachment 45298

okay cool I will take a look.

 

[4x15mph]

Okay but look closely or you will look right over them... I did since they were clogged. Use a paper clip and once you think you have it clear, put a compressor on the hole and make sure you have a complete thru hole.

 

[Kathy]

Whoohoo now the work begins - parts are back. UPS man didn't even make it down the driveway with the box

 

[4x15mph]

Please document the process and I am almost as excited as you about the parts showing up. I can't wait to see this project in motion since I expect to do this in the future.

@Kathy, for the wires that you replaced, were they easy to take out of the CDI box? I opened my CDI box up once and saw a wire's nest which had me closing the cover real quickly! I would like to have new wires for maintenance reasons, plus they make the boat look faster

 

[Kathy]

Does anyone know where to get torque specs for these motors

 

[AZDANSX230HO]

Does anyone know where to get torque specs for these motors

What specs do you need? Cylinder, heads?

 

[AZDANSX230HO]

You can download the service manual here for $ 9.50 or I can call a buddy of mine who is a jet ski mechanic.

http://www.repairmanualguru.com/YamahaBoat.htm