Thread: Issues after complete rebuild...
02-11-2011, 03:15 AM #1
Issues after complete rebuild...
So, I've completely rebuilt my '07 RXP engine and put one hour of break-in time on the seat. I've installed new Riva pistons, I had the valves resurfaced, replaced all of the plain bearings, replaced both oil pump's components, replaced the oil/water pump seal, replaced the magneto, replaced the double gear, replaced the timing chain, replaced the cam gear, spec'd and polished the cam and the crank, new head gasket, rebuilt the supercharger with 12.5ft lbs of slip ... etc and so on and so fourth.
The ski runs ok - no major symptoms. Now, here are my issues. At 8300RPM it falls flat on it's face and doesn't have the "kick" like it did before the rebuild. What also concerns me is that - the plug in cylinder #3 is discolored. ok The compression is @ 135psi in all three cylinders after my test run, my oil looks good (not milky), I found a half of a tablespoon of pure gas in my catchcan, my coolant tank was down an inch - which may just be air farting out of the hoses, or leakage into the combustion chamber - I know it wasn't being forced outta my coolant tank.
My thoughts on the discolored plug - either problematic injector on number three or coolant getting into the combustion chamber.
My thoughts on the "falling on it's face" and lack of "spunk" performance issue - either TPS problem or f'ed up cam sprocket timing. - can't be boost leak - can't be slipping washers.
For some reason I think the two issues are unrelated, and I want your opinion on what to do next.
P.S. Here are my plugs after 1 hour #3, #2, #1.
Last edited by Craigo; 03-09-2011 at 12:55 PM.
02-11-2011, 05:43 AM #2
- Join Date
- Sep 2009
- Aussie Land
Well its obvious that there is something 'more' getting burnt by that plug than the other 2.
Maybe try switching the injectors around to see if its a sticky injector? At the same time put 3 new plugs in and see if the colour follows the injector?
Coolant USUALLY doesn't discolour brown, but its only 1 hour, so I cannot be certain.
Does this help?
02-11-2011, 06:24 AM #3
IMO 12.5 ft lb of slip is nowhere near enough with the X charger your using and higher 8600ish rpm your looking to run.......im not saying your charger is already slipping BUT i know i wouldnt set the X charger up with anything less than 14-15 ft lb..........im not saying its the problem but it is high rpm where u say its not performing and thats where the washers would begin to slip if the clutch slip were not set tight enough....like i said its more than likely not it but could be and i would set it higher now so it breaks in around 13+ ft lb with that charger @ those RPMS's....good luck either way!
02-11-2011, 06:28 AM #4
Sounds like the same problem i had after rebuild Craigo. once i got my cam timing correct it still was down on revs and found TPS to be out , still don"t know what caused it but was out so i reset and my RPM"S and power was back so would try that for starters. With the plugs its hard to tell from the picture but 1&2 look a little lean and 3 is a little rich so swap them around and see if the same. I just seen a RXP here with similar plug colour on one plug and turned out to be a boost leak from the oring on the injector where it goes in the manifold. We only found it by spraying carby clean around the manifold !!!!!
02-11-2011, 07:59 AM #5
TPS reset is a good thought.
Do you have any other injectors to try? Borrow a friends injectors and see what happens. I had a failing injector cause RPM drop.
02-11-2011, 09:05 AM #6
02-11-2011, 08:34 PM #7
just verifing, you ran it @ 8300 after an hour? thats what your saying right. in bursts or long runs?
02-11-2011, 09:10 PM #8
That thing will make more power as it breaks in. Also are weather conditions similar to last time you where out?
02-11-2011, 10:29 PM #9
Could a failing injector in number 3 make a plug look like it was rich?
I was not sure what a leaky or sticky injector would look like.
Obviously if the injector was down on flow it should look leaner.
02-12-2011, 02:14 AM #10
I want to thank everyone for helping this greenhorn! The next part of my troubleshoot will include -
1) Up-ing the slip on my charger to 15ft lbs. Thanks Steve!
2) Checking my TPS with buds. Thanks Sniper300 & dhoad!
3) Re-arranging injectors and installing new plugs. Thanks lolzer & dhoad!
4) Fire it off cold and hold it at the limiter for 3 minutes on the trailer - just to see what happens. -
Note: The thing that bothers me the most about my build was the head gasket install... I've never installed a head, but I don't think the bolts felt like they tightened evenly. I didn't check the head myself and my machinist said he checked it - but he was tired of me bellering at him (while waiting for 2 and a half months to get my shit back) - he handed me my head without offering to add an expense to resurface it - so I'm not sure of it's trueness.. I'm thinking about a ReDoo on the head setup.
Anyway, it feels good gettin my "hands dirty" that's the only way I've ever been able to learn anything - it's just time and money, right!
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