Won't rev over 5000 rpm

AMCQ46 · Post by **AMCQ46** » Fri Jun 03, 2016 4:11 pm

and you checked the cam timing to make sure it wasn't 1 rev out?

VTRDark · Post by **VTRDark** » Fri Jun 03, 2016 5:03 pm

This is the classic 180 degrees out. You wont notice any change while revving at a stand still and it only shows itself under load. Have you removed the rear cams and spun it over and replaced the cams like I said in the post above. Turning the engine over without removing the cams beforehand will make no difference at all. All timing markings will line up regardless. It really is a simple job and as easy as 1 2 3. It most likely sounds more complicated what I described above but I wanted you to be clear on everything. 1 hour later you will be back up and running above 5000.

Stop chasing your tail....remove those cams and turn the crank over 1 revolution and replace cams

More Info
http://www.vtr1000.org/phpBB3/viewtopic ... ut#p299240

8541Hawk · Post by **8541Hawk** » Fri Jun 03, 2016 6:46 pm

His way (or Rogers instructions) is the "correct" way to set the cams per Honda. That is the procedure that is listed in the service manual.

The whole setting the rear first came about while fitting CCTs for folks who didn't want to remove the front valve cover.

Anyways it sounds like a fuel flow issue. As the carbs have been changed I would suspect the fuel petcock or screen.
The diaphragm could have a pin hole or small crack or possible the manual shut off isn't all the way open.

In any case I would not worry about or mess with the cam timing at this point if it was my bike.

Thetoaddude · Post by **Thetoaddude** » Sat Jun 04, 2016 4:08 pm

Good news - cams removed and replaced 1 turn of the crank later, no problems.

Bad news - no difference in performance. Revs still hitting a wall at 5k.

lloydie · Post by **lloydie** » Sat Jun 04, 2016 5:02 pm

Has it got a limiter fitted ?
Or 33bhp restrictor washers under the carbs ?
Is it a uk bike ?

VTRDark · Post by **VTRDark** » Sat Jun 04, 2016 5:13 pm

No way...for fooks sake. I was sure that was it. 5000 revs is bang on where the 180 out issue takes affect. Did you put the cams back where they where afterwards. If not you will need to put them back the other way again. I'm really sorry about that but at least it can be ruled out. Maybe it is a fuel issue after all then, other than that electrical. I can only start taking guesses now but fuel petcock would be worth testing.

8541Hawk · Post by **8541Hawk** » Sat Jun 04, 2016 5:32 pm

At this point I would look at 2 possible issues.
Either the petcock, which would be the most likely cause or the Pulse Generator Pick up could also cause the issue.

:beer:

lloydie · Post by **lloydie** » Sat Jun 04, 2016 5:58 pm

8541Hawk wrote: At this point I would look at 2 possible issues.
Either the petcock, which would be the most likely cause or the Pulse Generator Pick up could also cause the issue.

This man knows his sh1t [THUMBS UP SIGN]

Wicky · Post by **Wicky** » Sat Jun 04, 2016 6:11 pm

Also look at the air filter, and try a new un.

Thetoaddude · Post by **Thetoaddude** » Sat Jun 04, 2016 8:43 pm

Ever had one of those days?

Having failed with the cams I've gone back to look at everything else again, clearly I've missed something.

The screws holding the velocity stacks were on their last legs and I really should have replaced them. I didn't. Now I've rounded 2 off. Drilled them but ended up bashing the threaded blocks out the bottom of the air box to remove the last of the bolts on the bench. Epoxy to hold them back in is now drying.

Have now spotted that the inlet rubber on the front carb wasn't seated properly

Not proud, apologies to all you guys who have tried to help. At least I can be a lesson to others - check, check again, sober up, then check again.

Now where's that wine bottle?

Thetoaddude · Post by **Thetoaddude** » Sat Jun 04, 2016 8:46 pm

Oh yeah, let the piss taking commence!!!!

lloydie · Post by **lloydie** » Sat Jun 04, 2016 9:10 pm

Not the first to put a rubber on wrong !!

tony.mon · Post by **tony.mon** » Sat Jun 04, 2016 9:14 pm

Well, at least you now know how to set the cam timing.

Good on you to report what it was

Hopefully, anyway.

A carb inlet problem usually leads to big misfires, not just not revving out.

Just a thought- when you reset the valve timing you did just change one cylinder, not both, didn't you?

Thetoaddude · Post by **Thetoaddude** » Sat Jun 04, 2016 9:39 pm

Yes, I have become "intimate" with my bike to say the least!

Only re-set the rear cylinder Tony, although I have to say it sounded and felt better despite the miss-fire today.

I'll make it all air tight tomorrow and see what happens. As you say, I'm fairly adept at fiddling with the timing so putting it all back holds no fear!

VTRDark · Post by **VTRDark** » Sat Jun 04, 2016 10:05 pm

Now where's my facepalm emoji...Doh.

Thanks for the update. Sorry to hear about the airbox, what a pain in the backside.

VTR1000.ORG

Won't rev over 5000 rpm

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