Crossflow 115 BIG issue

[Fisher29]

So about 2 years ago I bought a NorthStar 17ft with the turbojet 115, Motor had the performance kit and the stariner and it ran great (vro was disconnected). The year I bought it I relized the muffler adapter was cracked because one time it bogged down and it was shooting water out the mufller, had to limp it back to the launch like this. Got it welded, used all of last summer and it worked great, always fired right up and ran good, only isuue is it was only topping out at 30mph if that with 2 ppl. When I got the boat comp was 120 on all 4 and it feel like it was more powerfull back then. Took it out today and ran good but still felt sluggish, test the comp when I got home and all 3 are at 110 and cyl 1 is only pushing 25psi, I think I was running like this all last summer aswell, and the spark plugs on the 3 that are ok are in perfect shape (burn wise) the other one with 25psi is black. I was weary as of why that 1 plug looked bad last year but didnt bother with it, guess I know why. Hows it possible to run pretty well just on 3 and why is that 1 so far down. Not even 80 psi but barely 25. Any help would be appreciated. Im handy so will be doing rebuild myself if needed.

 

[jimmbo]

Time to pull the Bypass Cover on the Weak Cylinder and see if any of the Rings are Broken or Stuck . Press on the Ring with a flat Screwdriver, being careful not to slip. A good Ring will have a springy feel, while a broken one won't. A stuck ring won't budge. It also allows you to look at the Piston and see if there is any Scoring/Scuffing

 

[racerone]

You have a blown head gasket or broken rings.----Pull cylinder head.----You need 4 new pistons.------Broken rings is the most common failure on these.----It will happen to every crossflow !!

 

[Fisher29]

Got up early this morning to start working on it. Removed the bolts of the bypass cover but wasn't able to remove it no matter what I did, didn't want to crack it so left it alone. So I started to pull the motor, when I get home I just got remove the wiring and pull the 3 bolts that hold it in. Then once out ill pull the head off. Hopefully I can get away with just a hone but with it having no comp practically I think it'd be impossible to but we'll see.

 

[racerone]

????----There are 4 bypass covers.----Each held by 6 screws 1/4 -20NC threads.----I say you need 4 new O/S pistons and rings.----That will give you real performance again.

 

[Fisher29]

????----There are 4 bypass covers.----Each held by 6 screws 1/4 -20NC threads.----I say you need 4 new O/S pistons and rings.----That will give you real performance again.

Yes im aware there are 4 bypass covers, one per cylinder. I tried removing the one on the low comp cylinder and it couldnt come off, I removed all 6 bolts and nothing. So I started pulling the motor out cause it deffinently ate a ring.

 

[racerone]

I have never had an issue removing a bypass cover.----Screwdriver in between the 2 covers and the one with no bolts pops off.

 

[Fisher29]

Thanks, Ill give it a shot and report back, Appreciate the help.

 

[Fisher29]

Alrighty, got the engine pulled and I got the head off as well, At first look the cylinder itself looked good, the edges of the piston were wavy but the cylinder seemed smooth to the touch, until I felt a little tiny (very slight) engrave patch by the exhaust ports thought I might be able to get away with a hone but, Guess ill need to bore em all and install new pistons. and rings.

 

[racerone]

I do not have enough fingers and toes to count how many times I have seen this damage.-----Thousands of these motors have failed due to broken rings !

 

[Fisher29]

I do not have enough fingers and toes to count how many times I have seen this damage.-----Thousands of these motors have failed due to broken rings !

Hahaha, Cant believe its still ran great enough for me to think it was just a fuel problem lol. Do you think I should go with Wiseco pistons, how do they hold up any issues?

 

[racerone]

Some will argue.-----I have had no issues with WISECO pistons.-----Rather use them instead of some made from ' chinesium " material.-----I believe Wiseco is a good product.

 

[Fisher29]

Now I just gotta find a machine shop in south central ontario

 

[racerone]

Where in south central Ontario ??----I might be able to suggest a shop.

 

[Fisher29]

Where in south central Ontario ??----I might be able to suggest a shop.

Well im in Newmarket but can take it anywhere really, Theres one in Orillia but the guy has a 3 week wait time. I was hoping to get it done in a week or 2 max. All the shops I called say its either to big or too small (motorcycle shops). What would you recocmend.

 

[racerone]

Wait for the shop in Orillia.-----

 

[Fisher29]

Does anyone happen to know the std bore size of this 115 crossflow?

 

[jimmbo]

3.500" for the 99.6 cu.in. 115

 

[Grant09]

Try Harrison Motorsports, in Peterborough, Steve @ 705-745-0186

 

[Fisher29]

So I took it to the shop in orillia last week and today they called me it saying it needs to be sleeved. Not sure why or if thats true but wanted to get your thoughts?