7,000 Rpm Stummble
09-16-2006, 10:17 AM
#1
Junior Member
Squid
Thread Starter
Join Date: Aug 2006
Location: Neenah,WI
Posts: 24
7,000 Rpm Stummble
heres the scoop,ive got a 98 hawk.i got the bike at work,the cam tens. came apart and banged the front 2 exhaust valves.the customer did not want to fix it,so i got a good deal.i took both heads off,ported both,new valves,cut .020 off the heads.installed factory pro jet kit,advancer,bmc race filter,put the tps at 500,removed pair system.the jets are 180f/182r,needles at 4th notch,50 pilot jets.
i get it on the dyno and it pulls great to 6,800 to 7,000 grand and starts to stummble,ive made it rich,lean-still there.ive changed plugs,put the tps back at 836(how it was),took the advancer out still there.i just put a new pulse generator in-still there.ive swapped booth boxs with another 98 hawk-still there!
ive got plenty of valve clearence.checked the valves a dozen times,there right on the money.when your out rideing every now and then it wont do it,it pulls great.
just wondering if anyone has a IDEA?
i get it on the dyno and it pulls great to 6,800 to 7,000 grand and starts to stummble,ive made it rich,lean-still there.ive changed plugs,put the tps back at 836(how it was),took the advancer out still there.i just put a new pulse generator in-still there.ive swapped booth boxs with another 98 hawk-still there!
ive got plenty of valve clearence.checked the valves a dozen times,there right on the money.when your out rideing every now and then it wont do it,it pulls great.
just wondering if anyone has a IDEA?
09-16-2006, 10:27 AM
#2
Senior Member
SuperBike
Join Date: Aug 2005
Location: Fort Wayne, IN
Posts: 1,858
That sounds exactly like what mine was doing when I had the cam timing wrong. I had the rear cams out by 180° (360° of crankshaft rotation). This caused the rear cylinder to fire 90° of crankshaft rotation after the front. I suspect that the airbox cannot supply both cylinders when they are basically trying to fill at the same time. You should take both cam covers off and check the timing. I actually found mine when checking the clearances, so using that process of turning the crank to the different position indicators should show you if there is an issue.
Question - Does it sound funny? Mine did not have the booming sound of a normal v-twin when the cams were installed wrong. It was more like a big dirtbike.
Question - Does it sound funny? Mine did not have the booming sound of a normal v-twin when the cams were installed wrong. It was more like a big dirtbike.
09-16-2006, 03:03 PM
#4
Senior Member
SuperBike
Join Date: Aug 2005
Location: Fort Wayne, IN
Posts: 1,858
It sure sounds like your cams are 180° out. Go through the Honda manual's procedure for checking the valve clearance. Set the flywheel at the correct spot and check the front cam sprockets for proper alignment. From there be very careful and follow the instructions to the T. If your rears are pointing in and not out (like mine were) then you've found your problem. You must have both cam covers off and follow the procedure correctly. I tried to cheat and only take off one. It was really frustrating when I found it because I realized what a bone-head I had been. I've built many V engines and installing the cams wrong in the first place was a rookie mistake. That's ok because mistakes happen, and it's easy to do. The frustrating part was when I'd realized that my laziness caused me to miss the real problem.
I hope this helps!
I hope this helps!
10-16-2006, 04:42 PM
#6
Junior Member
Squid
Join Date: Sep 2006
Posts: 13
wplfeman
heres the scoop,ive got a 98 hawk.i got the bike at work,the cam tens. came apart and banged the front 2 exhaust valves.the customer did not want to fix it,so i got a good deal.i took both heads off,ported both,new valves,cut .020 off the heads.installed factory pro jet kit,advancer,bmc race filter,put the tps at 500,removed pair system.the jets are 180f/182r,needles at 4th notch,50 pilot jets.
i get it on the dyno and it pulls great to 6,800 to 7,000 grand and starts to stummble,ive made it rich,lean-still there.ive changed plugs,put the tps back at 836(how it was),took the advancer out still there.i just put a new pulse generator in-still there.ive swapped booth boxs with another 98 hawk-still there!
ive got plenty of valve clearence.checked the valves a dozen times,there right on the money.when your out rideing every now and then it wont do it,it pulls great.
just wondering if anyone has a IDEA?
i get it on the dyno and it pulls great to 6,800 to 7,000 grand and starts to stummble,ive made it rich,lean-still there.ive changed plugs,put the tps back at 836(how it was),took the advancer out still there.i just put a new pulse generator in-still there.ive swapped booth boxs with another 98 hawk-still there!
ive got plenty of valve clearence.checked the valves a dozen times,there right on the money.when your out rideing every now and then it wont do it,it pulls great.
just wondering if anyone has a IDEA?
11-02-2006, 03:49 AM
#9
Junior Member
Squid
Join Date: Sep 2006
Posts: 13
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