new owner with a few problems [Archive] - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums

: new owner with a few problems

06-19-2005, 09:34 AM
I have had my VN since last sept and it has recently developed a problem or two...

First there is an odd noise - a chirpy tweeting noise like a toy bird whistle. It kicks in at 3000 rpm or so. I'm wondering if this is the cam chain but the sound isn't what I would describe as 'rattle' or 'slap'.

The second problem is more worrying. The bike has no real power until the engine reaches about 6000 rpm then suddenly, WHAM, the bike surges forward. As soon as the rpm drops, it loses power again - the engine is running and sounds ok but it doesn't seem to be transferring much power to the wheel. Pulling away at the lights is embarrasing, the engine makes a load of noise but there is almost no acceleration.

I am worried that this is a clutch problem but a friend suggested it might be something to do with 'timing'? I don't know a great deal about engines so I would like to work out what the problem is so I don't get ripped off if I have to take it to a mechanic.

Thanks in advance for any advice.

PS can anyone recommend a manufacturer for 18mm sockets that I can get in the UK, one with a small outside circumference to get at those deep plugs?

pps can anyone recommend a maintenance free battery that I can get in the UK. The Yuasa and Westco are impossible to find locally.

06-20-2005, 04:30 PM
An update.

I have changed the oil, plugs, put in a new battery and Grambo'd the ACCT's. No change in either the noise or the power issue.

If anyone out there has any ideas I'd appreciate them.



Loran in Npvl IL
06-21-2005, 09:42 AM
The VN750 doesnít have any timing adjustments unless the engine was disassembled. Do you know the history of the bike? What year is it?

Something else you can check are the air cleaners to make sure they still exist and are properly oiled. The next easy fix, would be some gas additive like SeaFoam or Techron (sp?) but I donít know if those are available to you.

You said you changed the oil recently, after putting on another 50 miles, does the oil in the window still look clean (wished we had a dip stick)?

06-21-2005, 03:29 PM
Thanks for your thought Loran.

The bike is a '94 A9 UK model. I don't really know the history of the bike. The previous owner says he maintained it well and he has chromed it quite a bit.

Althought he problem developed quite suddenly, I can't think of an incident that might be the cause - no drops or anything like that, it makes me think it is a wear and tear issue.

We have Redex in the UK which is supposed to clean the carbs etc. I have run a couple of doses through the engine but it hasn't helped.

The oil is still clean but I am gonna get a tube an pull a sample from the engine to see if it has particles in it.

I am going to check the air filters at the weekend so I will post back the results then.

In the mean time, any other ideas???


Loran in Npvl IL
06-22-2005, 10:06 AM
You may have to pull and disassemble the carbs to make sure all the jets and passages are clear/clean.

You said you used carb cleaner. Is it the gas additive type? If not, you may have ruined some rubber parts in the carb. Under the chrome top caps of the carbs, is a rubber diaphram (with a slider attached). I know of a few people who have used carb cleaner and ended up with holes in their diaphram. Just something else you can check.

06-22-2005, 12:37 PM
I am wondering if the "chirping" noise might be the clutch? what type oil are you using?

06-22-2005, 01:27 PM
Redex is a petrol additive designed to clean carbs etc. It shouldn't have damaged the diaphrams. As I understand carbs, each carb has two or more jets and the fuel flow throught the jet is controlled by throttle position?? The power problem I am having occurs at any speed and throttle position, the only constant seems to be the rpm.

I said earlier that I couldn't think of any 'incidents' but my girlfriend has just reminded me of 'The LEAK'. About four months ago my oil filter burst, a combination of corrosion and internal pressure (the previous owner had used a filter from a VN800 which is smaller than the filetr for the VN750) I replaced the filter withone of the correct size and topped up the oil. It seems that I had lost more oil than I thought. What prompted me to do the total oil change a month ago was the fact that the clutch was snatching in first instead of slipping. I reckon the clutch had been running dry all that time and the plates are now screwed.

Ok everyone. is rebuilding a clutch a doable job for someone with little experience, few tools and no garage? Or should I take it to a mech?

I'm sooo stupid.

Thanks for the advice though.

06-22-2005, 10:46 PM
I have a similar noise in my '86. It occurs between 3000-4000 only after the engine is really warmed up (10+ miles). My clutch is okay and the noise occurs while the clutch is fully engaed so I don't see how that could be the source. I hope you find it and let me know.

Loran in Npvl IL
06-24-2005, 09:44 AM
One of the quirks of the VN 700/750 is a grabby clutch when cold. Some refer to is as a coffie grinder sound when starting out. It can be fixed with a clutch replacement. It is recommended to use kevlar clutch friction disks and heavy duty springs. Some replaced the friction without replacing the steel plates due to costs. From what I have read on the yahoo board recently, no special tools are needed (except for a torque wrench) - you don't have to remove the clutch basket - use a dental pick, longnose plires, or other tool to remove all the plates. Before you mess with the clutch find out why there is a lack of power. No use throwing money away if the motor is bad.

07-10-2005, 06:34 PM
Well, the weather has finally been good enough for me to open up the clutch (I have no garage so have to work outside). Although there is some circular scoring and pitting on some of the steel plates, none of the plates are warped. The friction plates while worn still have plenty of friction 'stuff' left on them and the housing doesn't seem damaged. In short, there doesn't seem to be anything wrong with the clutch. I haven't refilled with oil yet just incase I have to open the engine again but I suspect that nothing will have changed just because I have reinstalled the clutch.

Back to square one. The power problem does not seem to be a transmission problem so it must be a creation problem. What do you think I should check next?

Btw. dr_knight, The oil I am using is 5w40 synthetic but I have only used this since the problem started but I have been reading about Halfords Oil and additives here ( here ( and I wonder if Halfords Oil is the problem since the oil I put in after the filter blew was Halfords 10w40 semi. Do you think it is worth trying some proper motorcycle oil? Neither the 5w or the 10w is marked as being 'energy saving' or having any friction reducing additives.


07-10-2005, 10:34 PM
scott ; did you check the clutch springs when you had your cluth apart? if the springs are weak this could affect the operation . the shop manual has tolerances for the springs. ken in penfield new york

08-23-2005, 04:37 PM
Well, the bike has been back on the road... briefly. I decided to follow your expert advice and replaced the clutch plates. I decided against splashing out on Kevlar and instead bunged in a set of cork (??!!) plates by EBC and whaddya know, it works. I hasn't however solved the odd chirping noise.

Since then I have had a mysterious rear flat and now have a snapped throttle cable. The tyre thing was weird, it was fine when I left home on a 140 mile round trip. By the time I had gone about 50 miles at high speed, I was experiencing some 'bouncing'. I have never ridden on a flat before so this was a new sensation - because the back end was flopping over the tyre from side to side, it actually felt like the bike was flexing in the middle! A pretty damn scary thought at 90mph. I got off the motorway and called the roadside rescue who came out but couldn't find a puncture. He put air in it but it didn't go down again. Still no idea why it went flat in the first place.

Now the throttle cable has snapped and its off the road again till I find spares to fix it with.

I hope your bikes are more reliable than mine :-)


08-30-2005, 10:25 PM
I had a similar problem on the oppisite side of the rpm range...
I had plenty of low end power but the bike was not capable of going over 70 mph unless going down hill... There was no power in the higher rpm range. I ended up moving the clip to a richer position on the needle jet and went up 2 sizes on the main jet and man the thing is a beast now :)
I would let the bike idle until warm the shut it down and check the spark plugs. Tan is good and means you need to check elsewhere... black and you are running too rich try turning the adjustment screws in... If the plugs are virtually clean then you may be running lean, try turning the adjustment screws out...
Hope this helps :)