06-12-2006, 04:11 PM #1
Mudbug Problem - Opinions Welcome
I went to the Mudbug after performing the following mods on my '03 1300r with a 13/19 prop:
R&D 45cc heads
R&D Race Filter
1200 intake grate
Jetworks kit (duckbills and syphon tube)
Intake tunnel reinforce.
The rpm's had been steadily building as I put it together. The last mods I did (Jetworks and removing the syphon spout) actually raised my rpm's from a peak of 7340 to 7390 and a speed at mudbug of 69 mph at half a tank. I had great hopes of changing my prop there to bring down the rpm's and improve the speed. Rob from Georgia offered to help me bend the new prop. It wouldn't happen as I lost 200 rpm's, 2 mph, and 60 psi on cylinder # 3. Before the trip I was at cyl1- 148, cyl2- 148, cyl3 -150.
After the rpm drop, cyl3 was at 90 psi. Adding oil only raised it up a few psi. Plug 1 was caramel, Plug 2 was a little darker caramel, Plug 3 was dark (blackish) with grit on it. All were dry. I pulled the head on cyl-3 and noted that the head looked good, the piston TOP looked good, and I could feel grooves on the cylinder wall. There were no outright gouges, but I could definetely feel a low spot (see picture). Just for grins, I cleaned up the head gasket, sprayed it with copper seal, and tried again. No joy.
I guess my question is (finally), what looks to be the culprit and what is the best way to go from here?? I will pull the cylinder and check the piston as soon as I get a chance. Assuming the ring is damaged, and I see nothing outright as of now, should I renik and replace the piston? ( I have an email into Millenium) Should I send the cylinders off for porting and renick, etc, etc.? Which way do y'all recommend I go?
My EFI settings are 7,7,2,9
06-12-2006, 05:04 PM #2
If it's a severe enough groove to lose PSI, you need another cylinder and rings. Post a request on the "Looking For" area, someone will have one. Make sure you check your piston when you pull the jug, and make sure any cylinder you install matches the piston.
06-12-2006, 05:17 PM #3
Steve, call me when you get a chance. I have a deal for you
06-13-2006, 07:25 AM #4
- Join Date
- Jul 2006
The cylinder may just need to be cleaned with acid and replace the rings. But you need to find out what caused the problem first. How do the other cyl look? Call Lowell Horning he will be able to help you out.
06-13-2006, 08:10 AM #5
Re: Mudbug Problem - Opinions WelcomeOriginally Posted by howestek
06-13-2006, 09:14 PM #6
Re: Mudbug Problem - Opinions WelcomeOriginally Posted by Smitty
06-13-2006, 09:17 PM #7Originally Posted by John
06-15-2006, 09:03 AM #8
I meet you at the dock after you took your head off.
Get a magnifying glass and look deep down in that plug and look for detonation.
You have lots of fuel on the bottom and lots in the mid range and very little on top.
Please let us know what you find. Also how many hours did it last ?
06-15-2006, 09:54 AM #9Originally Posted by mtrager
As far as fuel, I played with the red settings and saw no rpm difference between 1 and 4 so I backed it to 2 to be safe (maybe not safe enough!) It seemed to jive with what other board members with unported skis were reporting.
I would say that it lasted, in this configuration, about 7-9 hrs. 3 hours with the jetworks.Total engine time about 77 hours. As a side note, until the bug, I had been running 93 octane exclusively. At Doirons landing, all they had was 92. I assumed that would be sufficient. Surely that wouldn't cause deto? If it did, I probably wouldn't be the only one having probs.
Thanks, and I'll let ya know what and if I find something.
06-15-2006, 11:06 AM #10
My setup is pretty close to yours and I run 92 octane but my rpm's are only about 7200 After reading this post I got myself a compressions checker and will she what she has tonight.
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