20 Most Recent 1994 Yamaha YZF 750 R - Page 2 Questions & Answers

Seems that the crank/timing settings needs a closerr look than to feel that the carb is faulty.The engine is becoming rougher because the firing angle is changed. I also doubt that the carb /jet kit be replaced back with the original as the new jet is not matching.
Now start the engine and set up idle to more than minimum so that the vehicle does not stall but is somewhat smooth. Now try to advance/****** the timing and notice if the engine becomes smoother irrespective of the TDC settings. If so set to the best level and bring down the Idle , do not reduce off air but check the mixture at the exhaust to have this done all over.
Somewhere in the new change a point has been missed..

Since all four light at the same time you have a short. Check the wires near the turn signal switch and then the switch itself. Keep following the wires until you find the short if switch tests okay.

check all vacuum lines you could have a manifold leak...buy some Chemtool B-12 form Autozone if they have any left ..Caution, its highly toxic has MEK in it, use gloves and masks..cleans frame, rims, carb even road tar off you cars paint and its also good for detecting leaks when you spray it around carb hoses..dont use a lot on painted surfaces in the same area.. if that doesn't fix your problem then while your at the Autozone pick up a can of Seafoam and pour 1/3 can to two gallon gas and get on it for about 10 miles and see if that doesnt restore your power..can of Seafoam is $10, i've used it in my car too when it was having trouble starting and it worked fine. I had a similar problem like yours before i new about Seaoam, but it would'nt have helped me though..i bought a salvaged carb bank and cleaned up the bowls tweaked the pilot jet another 1/4 turn since i could get to it easier and man it now rides like a liter bike. i tore the old one apart to see why it was running so bad and when i took off the number one bowl i heard something rattling around in it...the main jet had fallen off! so there are some options . Can i get some feeback? thanks.

I would try borrowing a coil first to see if it is a coil problem, Yamaha CDI units are pretty durable and seldom fail whereas coils are quite a common fault and relatively cheap.

Look at the base of the cyclinder where it bolts to the block. It will tell you what CC it is.

Probably the belly pan mounting bracket is bent

The Key code is only on a tag that comes with key set. if it was not saved or written down in manuel there is no other way to get it.

pull a lock nut/nyloc nut on the over side if the bolt is long enough if not use thread lock just dap a bit on the bolt and screw it in and let the stuff set good luck bud

There are 4 rubber spark plug caps on top of the engine's cylinder head behind the radiator.
If you pull them you reveal a hole on each one.Inside that hole you insert the 16mm spark plug wrench tool which must be long enough to reach them.

You have air leaks in the intake that are causing the bike to run lean and idle fast. The 2nd carb problem is probably a pin hole in the CV carb diaphragm.

A “very helpful” rating for this answer? Thanks!

You may have a bad piston and oil may be getting by.

If memory serves me correct, it doesn't have one. A light comes on when getting low on fuel. Should get about 130-150 miles out of a full tank

Set the fuel mixture screw at 2 1/2 turns out. pilot screws 3 1/2 turns out, & the Dynojet 118 main jets had been installed.Stock jets are 122 according to the Haynes manual.
set the float height at 12mm, ---------- Mains - 182/172 stagger
Needles - stock
floats - 12 mm to 14mm
pilot jets - 38 (one size above stock, #35)
pilot screw - 2 turns out.----------- ------------ Also click this link for ,more help:-- http://technoanswers.blogspot.com/2011/06/pilot-jet-setting-yamaha-yzf-750.html -------------- This should help.Thanks.Helpmech.

Hello,

There could be several things that would cause your problem;

Wrong spark plug gap - too wide
CDI - The capacitive-discharge ignition uses capacitor discharge current output to fire the spark plug.
Bad gas

I would start by stabilizing your fuel to see if this is the issue. Buy a can of Sea Foam and a bottle of Sta-bil fuel stabilizer. Follow the directions on both of these items when filling your tank (use both together). Use premium fuel when filling up for this time. Run a full take through your system. When filling up again, you may use a lower grade of fuel if you want, but use the Sea Foam again. The Ethanol added to fuel these days can cause valve deposits that will lead to engine issues. You don't have to use the Sea Foam in every tank of fuel you buy - just use it once or twice a month.

Hope this helps. If you find this information helpful, please vote on this post.

Regards,

Oz

Hi,

For that, you could Refer to :-

http://viragotech.com/XV750/750viragotechinfo.html

I also Found a Place where you could buy the Service Manual for less than $10 as Compared to other Sites or Vendors charging more than $50.

http://www.tradebit.com/filedetail.php/1128289-yamaha-virago-xv750se-xv750-xv-750-motorcycle

Let me know,if needed further assistance.

Hope i helped you.

Thanks for using ' Fixya ' and have a nice day!!

Turn to the side and then engage the lock with the key.(you may need to push key in before it will lock)move it a little to the left or right to let the lock fit into the handle bar lug.

this is fuel to rich a lot on carb will be a screw turn this in all the way in and unscrew 2 turns this is the mixture screw and get back to me if not ok