Twisted throttle - dies, Top end Engine Noise - near my wits end

I was still having trouble with engine noise (the noise is still there and I am at my wits end with this bike) and decided to remove and clean the oil pump and then check the pressure. I managed to do the job and then start up the bike. Now for some reason it starts but when I twist the throttle it stalls at about 1500rpm. This hasn't happened before and I was wondering what may cause it. The bike sat for about 2 months before I started it. Battery is good. Charging system is fine. I did not adjust the carbs. Any thoughts?

I though maybe a lack of oil pressure was causing the loud engine noise but it isn't (I removed and cleaned the pump and added the oil filter mod). I fixed the exhaust leaks, added new cam tensionrs, adjusted the valves twice and still the noise. Cams are in very good condition. I am near my wits end with this. Any ideas?

I have been working on this bike for over 3 years.

 

how many miles on the elderly beast ? check fuel flow to carbs. hey, they all make some noise, right ? cleaning the oil pump ?? thats weird and not necessary.

 

43,000 I am thinking about hauling the engine out again and rebuilding the top end. I pulled the engine out once before to add a spring one of the rockers. Jut trying to figure out what may be causing the noise. Valves? Cam Chain? Rockers? I couldn't find anything loose except for the one spring missing on a rocker.

 

one thing you could try: remove the valve adjusting screws, and check the bottoms for wear and distortion. consider replacing them.

 

That is a great idea - thanks. A found a video from a guy with a Magna and he had that problem.

 

some screws are flat on the bottom, others are hemispherical. in either case they get hammered, and wear will accumulate with mileage. the worn, distorted tip will be hard to adjust and wont hold the adjustment long and be noisier than usual.

i believe new screws are available and inexpensive.

 

What are the #s for the charging system checks?

 

Close to 14 volts when running.

 

With shipping it will cost me about $130 CDN for 16.

 

There's a lot more to the check than that. Search the forum to see how to easily check auy potential ground, AC output, DC output, etc., when hot and cold.

 

How much was shipping!? Also, which bike are we talking about?

I replaced all of mine on my VF500F over the winter just because it was sitting there out of the bike. They were $2.38 each from Partzilla https://www.partzilla.com/product/honda/90012-333-000?gad=1

Granted--none of them actually needed replacement.

 

inspect yours for wear and possibly show photos of any damage.

 

seems like the flat bottom screws might wear less than the round bottom screws that often look flat-spotted.

 

Oh yea--I'm not saying that it's not worth checking out. I feel better knowing that mine were replaced. Just that at about ~25k miles or something my hemispherical ones weren't substantially deformed compared to the new ones that went in. One thing I will say while you're replacing them.. make damn sure you cover any areas that they could potentially fall into. I got lucky as hell I got a lucky bounce on one of them.

I'm more confused about why they would cost $130 shipped.

 

That is the price on CMSL. I haven't checked anywhere else but will. The price included shipping.

 

The bike is a 1983 VF750f

 

I am going to test the voltage when I am twisting the throttle and see if it drops before the stall.

 

The reason I did that is because I wasn't getting much oil flow out of the rear cylinder passage. I removed the banjo bolt and there wasn't any oil there. I turned the engine over and nothing came out of if. There was a good 1/4" of sludge, metal pieces and some gasket material in the oil pan and it was due for a cleaning anyway. The pump was fine.

 

seems like that might be related to some of the cam failures that era VF750 was infamous for. generally, finding any metal in the sump is alarming. sludge=poor maintenance. metal=OMG.

 

What type of noise exactly? Tapping, banging, chattering?