Thread: 97 GTX ?
08-25-2008, 07:16 PM #1
97 GTX ?
heres where im at, rebulit my 787 along with the carbs plus new DS,prop and wear ring. now when i was out two days ago it was runnin really good rpms were at 6750 , when i went out today it was hittin 6830 for rpms. does that sound too high? what is the normal rpms i should be seeing? i put in a hotrod crank and some prox pistons other wise it is stock.when i was loading it up i felt the pipe it was warm but not too hot and when i felt the head it was hot ,not scolding, but hot . is this a sign of runnin a bit lean?
Last edited by shawnIII; 08-25-2008 at 09:06 PM.
08-25-2008, 10:53 PM #2
rpms should be in the 6800 range depending on your set up. can run in the 6900's too if you have it dialed in. have you done any plug chops? that will tell you how the engine is running. if you run it wot for a bit and see the rpms slowly drop, then you are probably running lean. stock engine/carbs? what are the lows and highs set at?
08-26-2008, 09:43 AM #3
08-26-2008, 09:59 AM #4
sounds like it is set up pretty good. a plug chop is when you run at wot for 15-20 seconds and then pull the lanyard to kill the engine. remove the spark plugs and check them. they should be a milky-chocolate brown colour. this tells you how the engine is running at wot where the most damage can be done.
08-26-2008, 11:05 AM #5
i will head to the lake and do a chop today.
thanks for the info Z
09-01-2008, 12:52 AM #6
tryin to find what i feel is a major gas leak on this thing.
im going through 5 gallons in 50 min. i can smell gas in the hull but i cannot find the leak.
when its in my garage i see nothing leaking from hose clamps(i have switched out the grey lines) i have marked the gas line on the tank so it is not leaking from the tank.
the only thing i can think is it leaks bad when under load maybe?
nothing is leaking from the the carb gaskets either, but i have only checked while on the hose.
i suppose i could pull the air box and run the boat on the trailer at the launch.
5 gallons in 50min seem way excessive. before the rebuild i was able to get a full day riding 30mile up river then 30 mile back down.
the only thing ive changed on this is a hotrod crank and either half or 1 sized bigger prox pistons, but that shouldnt cause this much gas consumption, should it?
09-01-2008, 10:09 AM #7
- Join Date
- Mar 2008
That's normal gas consumption. That 787 engine is terrible about eating it. The manual for my 717 states that at WOT I will get 1 hr 8 min off of 12 gallons of gas. So 50 min for 5 gallons is not bad at all.
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