ninjette.org - View Single Post - Bike won't start and backfires when trying to start

TrickyTriggs · March 23rd, 2018, 10:16 PM

Hi guys, I'm back again and I am in desperate help!

I have a 1995 Suzuki RF900RS, it has over 40k miles on it. Bought from some guy who didn't take any good care of it. Valve's looked fine, normal ware on the camshafts, gearbox worn out(especially second gear). I have rebuilt a bike before but it was a two cylinder (GSTWIN) and I figured an engine with two more couldn't be that harder. I rebuilt the top end and did a valve clearance check. Making sure to keep the exhaust clearances between .20 and .10mm. And the intake between .10mm and .20 mm.

Procedure for cam timing:
-- Rotated the crankshaft to top dead center
-- aligned the 1st marker on the exhaust cam shaft, level with the valve head, counted 13 pins to the left along the cam chain and aligned the 3rd marker on the intake cam.
Here's the video of me doing that:

https://m.youtube.com/watch?v=d0x8A_ekqCg

-- Installed the cam tensioner.

Here the issue...

-- Carbs should have worked fine, they worked before I took the bike apart and after they should have kept working because I didn't do much to them at all.
-- When I start turn the fuel petcock on, fuel starts flowing. Take a good couple of minutes for the bike exhaust to make any kind of noise.
-- Bike immediately shoots of a loud gunfire(POP).
-- It will sometimes make a poomp, poomp, poomp, POP, poomp, poomp, poomp,, POP. And it will continue to do this unless I turn the bike off.
It also cause the exhaust to release a lot of white smoke.

Possible causes (I think):
Here's a bad video of the bike backfiring and not starting.

https://www.youtube.com/watch?v=RA68kj4kuQ4

-- Bad fuel: I was using months old fuel with fuel storage stuff put in it.
-- Bad Carbs: Which I have trouble believing because all the Pilot jets, main jets are clear. The diaphragm sliders work great.
-- Bad Spark Plugs: I replaced them with new ones
-- weak ignition coils: I tested each spark plug by grounding them to the frame and all worked exactly the same(lol I shocked my self once too, Not as bad as I thought it would be).
-- Stator: Not sure how it works and how it affects the spark plugs
-- Air delivery: I tried cleaning my stock air filter with K&N cleaner kit. By washing and spraying the product on it. I don't know if this could have cause the filter to get clogged instead of actually cleaning it. Which in turn could have caused the mixture to go lean. Therefore resulting in the combustion chambers to be flooded with fuel with not enough fuel burnet leaving a little of it still in the chamber. Causing backfiring.s
-- Some other stupid thing that I might have missed when reassembling the bike

ALL the motorcycle gurus out there I call on you for help!!!!

Thank You for any of the support you guys give me

March 23rd, 2018, 10:16 PM	#1
TrickyTriggs ninjette.org member Name: Tommy Location: Glastonbury Join Date: Nov 2017 Motorcycle(s): 1995 RF900R, 1996 GS500E Posts: 65	Bike won't start and backfires when trying to start FIXED!!!! Hi guys, I'm back again and I am in desperate help! I have a 1995 Suzuki RF900RS, it has over 40k miles on it. Bought from some guy who didn't take any good care of it. Valve's looked fine, normal ware on the camshafts, gearbox worn out(especially second gear). I have rebuilt a bike before but it was a two cylinder (GSTWIN) and I figured an engine with two more couldn't be that harder. I rebuilt the top end and did a valve clearance check. Making sure to keep the exhaust clearances between .20 and .10mm. And the intake between .10mm and .20 mm. Procedure for cam timing: -- Rotated the crankshaft to top dead center -- aligned the 1st marker on the exhaust cam shaft, level with the valve head, counted 13 pins to the left along the cam chain and aligned the 3rd marker on the intake cam. Here's the video of me doing that: https://m.youtube.com/watch?v=d0x8A_ekqCg -- Installed the cam tensioner. Here the issue... -- Carbs should have worked fine, they worked before I took the bike apart and after they should have kept working because I didn't do much to them at all. -- When I start turn the fuel petcock on, fuel starts flowing. Take a good couple of minutes for the bike exhaust to make any kind of noise. -- Bike immediately shoots of a loud gunfire(POP). -- It will sometimes make a poomp, poomp, poomp, POP, poomp, poomp, poomp,, POP. And it will continue to do this unless I turn the bike off. It also cause the exhaust to release a lot of white smoke. Possible causes (I think): Here's a bad video of the bike backfiring and not starting. https://www.youtube.com/watch?v=RA68kj4kuQ4 -- Bad fuel: I was using months old fuel with fuel storage stuff put in it. -- Bad Carbs: Which I have trouble believing because all the Pilot jets, main jets are clear. The diaphragm sliders work great. -- Bad Spark Plugs: I replaced them with new ones -- weak ignition coils: I tested each spark plug by grounding them to the frame and all worked exactly the same(lol I shocked my self once too, Not as bad as I thought it would be). -- Stator: Not sure how it works and how it affects the spark plugs -- Air delivery: I tried cleaning my stock air filter with K&N cleaner kit. By washing and spraying the product on it. I don't know if this could have cause the filter to get clogged instead of actually cleaning it. Which in turn could have caused the mixture to go lean. Therefore resulting in the combustion chambers to be flooded with fuel with not enough fuel burnet leaving a little of it still in the chamber. Causing backfiring.s -- Some other stupid thing that I might have missed when reassembling the bike ALL the motorcycle gurus out there I call on you for help!!!! Thank You for any of the support you guys give me Last futzed with by TrickyTriggs; April 8th, 2018 at 11:10 AM.