Slight issue today - bike started as usual with the cold start .... and only on 2 or 3 cylinders.
With all i have done this has to be fuel again ? blocked pilot jets or the likes.
It simply cannot be anything else.
So its carbs off again but I will do what one person said to a long time ago - put on a fuel filter
so i don't have to keep doing this.
This has to be the last time i clean the carbs as taking the airbox rubbers off is the most miserable thing to do
I am hoping the new fuel filter will save me from this !
When I bought my ZN700 in 2009, it only had 1,054 miles on it. It was part of an estate sale. The nephew of the original owner had tried to get it running right and gave up. I removed the tank, sloshed the gas around and dumped it and put it back on after cleaning the carbs. I then put a fuel filter on it and it flows well enough it doesn't cause fuel to run low at high rpm full throttle. I found my filter in an auto parts store. More recently I was going to replace it but the new one was much harder for me to blow through so I left the old one on. I suppose I should order one meant for a motorcycle.
When I bought it, it ran rough on 3 cylinders. (178 to 180 psig compression in all four cyl)I put a full can of Valvoline Complete Fuel System Cleaner in one tank of gas and ran the tank out. Afterwards it ran great on 3 cylinders. After verifying there was spark to the plugs, I pulled the carbs to clean them. that is when i found out the nephew of the original owner had attempted to clean them. They were looking clean so I ran weld tip cleaning wires through all the orifices and sprayed the orifices with carb cleaner. I also found a missing washer and a missing o-ring in two of the idle mix adjustments that I replaced. It still ran on 3 cylinders. So, I switched two of the spark plugs and the miss went with the plug. After putting in new plugs it ran great ever since for years with an occasional no start. Something in the start circuit is dirty I think. It acted like a dead battery. After trying it a few times it would always start. Maybe the ignition switch. During this winter after sitting for several weeks when I tried to start it, nothing happened just like a dead battery but it isn't the battery. I have to go through the start circuit and clean everything I suspect to get it to start. So, NO it isn't running at the moment.
The bike is now complete and that makes it different to work on , better for sure
than a bike missing bits. I only swore twice today - i miracle on this machine.
Due to returning to run on 2 cylinders i pulled the carbs (can do this in 5 mins now)
and cleaned them again. I have had far better results using carb cleaner than parts cleaner.
Far far better. I suppose its obvious but it has made a massive difference.
I will now always use carb cleaner on carbs - obvious really.
Fine sediment in the float bowls (all of them), which was not there a day ago.
A few holes blocked in various needle jets and possibly a pilot jet blocked.
The sediment must be the reason for the initial running on four and then going back to running on 2
I attach pic of sediment in bowl.
Someone months ago asked me to put on a fuel filter. The penny has dropped and i have ordered load for
all my bikes.
So with cleaned carbs, free fuel lines, fuel filter, a bike that 2 days ago ran on 4 cylinders immediately
after cleaning the carbs out, a charged battery , valve clearances in spec .... bar one that is slightly out,
plugs set, mixture jet richened in readiness to have to start with my knackered starter clutch ....
surely now it will at least start ?
If it does its balancing carbs, timing then the test ride.
Fuel elec connector wire off:
I attach a pic of a plastic connector where the wire has come off.
It is the one under the tank connected to the tank.
As you know elecs are not my string point.
Now how do i fix this ? I cant even get the flat metal connector inside out ?
Still have spongy brakes:
Have tried the vacuum contraption, reverse bleeding (this may have sorted the rear brake)
and the old faithful method but the front are still spongy.
All calipers were restored by myself , something i have done many times.
Going to have to bench bleed the brakes - whatever that is - never done it
or crack the joint bolts when under pressure to get this air out.
Day after cleaning carbs: Big day as fuel filter arrived through the post.
This had to work or else i would be totally stumped.
(Someone did say to me to use a fuel filter months ago too !)
So stripped totally the carbs, top and bottom, all jets cleaned and holes prodded with
thin wire to be sure they are clear, blown out too with compressed air from diving cylinder.
Carbs back on and all connected up fully - rubber inlets etc.
airbox and airfilter in.
sloshed the tank about and released a load of fuel from prime function hoping it
would get rid of sediment. (as per previous pics)
put on motorbike fuel filter (8mm) - cheap off ebay .. £3
connected tank up, no vent hoses (two of but not used), vacuum pipe to petcock, other vacuum pipe to plastic thing under tank (it went so much better like this ?), other vacuums blocked off. (the ones you use for syncing)
The usual squirt of cold start (my starter clutch is so knackered it only turns engine for a second ..) and it started ----- on 3 or 4.
Took it for a short run and runs on four. (it needs a good long run which will happen when mot'd)
Have the mixture screws 2.5 out.
It tended to rev when i pulled the clutch in and think this may need adjusting but the bike
needs a run of 5 miles to be sure and let it settle down.
So it works ! it starts now, runs on 4 cylinders , sounds sweet and tuned.
Goes like a rocket. Looks as cool as you can be.
The starter clutch issue is present but i will ignore this and get it tuned to perfection first.
I will buy another R1 engine and only then swap it out and then fix the starter clutch.
Brakes: They are better but in the end i gravity bleed them, vacuum bleed them -- every way of doing them
and they are better but not perfect. Def mot passable though.
Never known a bike so hard to get right on the brakes.
Job done ! I will post again when it is mot'd legal and inform how it went over a 20 mile run
and what tuning was needed. That is late next week.
phew what a journey !
Can there be a better bike to cruise to the coast on and eat some chips on ? No chance
unless it was a GS550e of course.
If you see me out on the road spraying cold start into the air box - please offer a jump start !
you should be proud of yourselves as without your help this would not have happened ! thanks again.
Spoke too soon ! Back to spluttering worse than ever now.
Think it is on 2 cylinders ticking over and might be on 3 or 4 revving up.
Stripped carbs twice and still exactly the same.
Swapped coils, checked timing , ht leads, spark - all ok.
wont tickover at all and races if i try and set the tickover when i pull clutch in
Whikst doing this wreck i have completed and tuned to perfection a gsx 250et
and a gpz600r. No problems there at all - they go with logic.
But this 750 i am absolutely totally stumped. I have done and tried absolutely everything
and thought i had it. It was parked up and running ok ?(not perfect but ok)
Anyway im leaving this now until next winter. I simply cant waste any more life on a bike
that has no wish to start.
Ill start up again from this point in December !
Its now riding weather and thank the lord i have a reliable gs550e !
Try a new set of spark plugs. They may have fouled.
It doesn't sound like this could be the problem but are you sure the tank is vented properly?
The engine in my ZN700 may be similar and I have my idle mix screws set at 1 1/2 turns out. That is where they were when I bought it and I kept them set the same since it runs great and gets good mileage with that setting.
I am parking the terrible running which may be carbs or electrics. I have no idea
but now i will sort to completion the starter clutch issue.
I will however when done do the plugs, vent checking and mixture.
A whirring when trying to start the bike. Not the starter motor.
Today i started this from a fully setup bike to the starter clutch on the bench in 4 hours.
This done with the bike on the center stand only (it actually helps as it is tilted and
allows access if lieing down.
I had no help and can be done alone.
I though the second i cant continue with the engine in ill simply take it out but that moment did
not come and don't think it will.
I will try and write this up but take it as said that it is possible with the engine in the bike - very possible.
Dont think about doing it without a electric torque gun as it allows in seconds to remove
the clutch hub nut and secondary shaft nut.
NOTE: One thing worth mentioning is when dealing with the philips headed bolts on the secondary shaft bearing cover
you need a big hit - not small taps. They are on tight and taps might (like mine) eat up the head .....
I was lucky and a massive hit got the offending one out.
The issues now are cleaning up the gaskets on sump and clutch cover.
This will be the most time consuming bit !
So Starter clutch now on the bench with a repair kit coming (£30)
I have been told to replace the starter clutch bit of the assembly (that comes out as one bit)
A new starter clutch costs £120 min.
One off ebay is cheaper but how can you tell if it too is knackered ?
My starter clutch looks fine ! I could not possibly tell if it was faulty unless i put it in and tried it !!!!
Is there a way to tell on the bench ?
Tomorrow i dismantle it and put in the kit (springs and rollers)
Tanked cleaned out and dried out. now runs clean and could almost drink water from it ...
It did contain fine sediment.
Carbs off, stripped, Soaked and almost boiled with lemon juice, all jets cleaned and new needle valve seat rubber and mixture rubbers put on.
Diaphragms all ok.
Carbs back on bike ready for the starter clutch.
Cleaned the engine gasket faces (Sump and clutch cover) with razor blade, wd40 etc. Now ready to be refitted. A seriously awful job especially as the engine is in ! Again however it is possible , well possible. The gaskets were stuck solid and the worst you could deal with.
Dismantled the starter clutch assembly.
On the unitrac engine:
No sign of any damage at all but one spring is bent at the end.
This is the one that was in and whirred and was almost totalled.
On my old R1 engine: (The spare wrecked engine)
Again looks ok bar it moving within the (cush drive type of rubber inside it)
When the repair kit arrives I wll use the best of both and hope it works.
If it does not at least when I take it apart again I won’t have the gasket issues. I am usually lucky using a bit of wd40 on the gasket surface which allows it to be removed again if a balls up……
If it does not work that will be it for a long while. Ill mothball the bike and only tinker with it to get it tuned if it starts.
Ok a few massive days but things are now back on track again:
Seemingly a horrendous job but I have now removed it with the engine still in the bike (very easy),
bought a repair kit of springs and rollers etc and repaired the old one.
So it is possible to removed the starter clutch with the engine in - easily too !
you need a electric impact gun, impact driver and a large socket for banging back in the
took me 3 easy days , due to waiting for parts etc.
Now running on 4 cylinders and bike can now start - due to the repaired starter clutch:
After the starter clutch worked i then was hoping it would start first time as
I have cleaned the carbs:
I actually boiled the carbs , the first time i have done this ..... i used water and lemon juice !
after this i cleaned the carbs with carb cleaner.
After i got the ht leads the right way round (i cant believe i make this mistake so often) it started
first time on 4 cylinders.
It starts perfectly now, wthout cold start spray.
took it for a spin and needs a tune but it runs like a dream.
What fixed this 2,3 cylinder stumbling this was simply a carb boil and new rubbers
in the mixture screws and needle valve bowls.
-Brakes spongy - i cant seem to get them right. if anyone has a sure fire way ? let me know
-Sump leak - i used an old gasket in my haste with the starter clutch - need to put a new one on
-Tune the bike - def not right but always runs on 4 now. (I wil try 1.5 turns out)
- I am sure the steering head bearings might need adjusting
But as you can see the bike is almost beaten into shape !
what a bike i is now running on 4 mind !
What carbs does the bike have. My ZN700 that is set 1 1/2 turns out on the mixture screws has Keihin carbs. If yours has Mikuni, they may be different. The way I used to set mixture screws on autos was to screw them in until the engine started slowing down and back them out a little. I haven't messed with the adjustment on my Keihins because it starts and runs so well where they are.
As part of the tuneup, you may want to synchronize the carbs after setting the idle mix.
You may have to run the engine a while to get all of the water or whatever out of the carbs. I rebuilt my auto carb one time by disassembling it and soaking it in a strong cleaner. Washed all of the parts with water. Then I blew off all of the parts and passages with compressed air and assembled it. I had to drive it for 30 minutes or so stopping occasionally to readjust the idle mix screws before all of the water was removed and it ran right. It ran noticeably stronger and I didn't need to rebuild it. It was running okay before.
My carbs are mikuni.
Haynes says 2 turns out. I had it at three and it might even need more to stop
it screaming when you pull the clutch in going along ? The needle height is at three.
Does this mean if you could raise the needle to get it back in spec ?
I on the next carb clean check the jets and if they are wrong ?
Pilot i am sure is stock 37.5
Ill check the needle, needle jet and main jet. I need to check again they are stock as i have a
(The main jet i swapped out said 425 on it and stock is 110)
Other issues: After my attempt to repair the starter clutch with a kit it did not work.
It is more usable but not right at all. So it does indeed look like if it goes you have to buy a new one - that looks like £120 !
I will however wait until the bike is running correctly before i do this again as it is a big
job and i simply must have this bike running reliable before i can get any enthusiasm
to do it.
Bought new connector box for tank twin elec connector.
Finally learnt how to dismantle these connectors and renew or repair them.
Stick on new sump gasket (easy as this bike has zero stripped threads now i have been over it)
Brake continue to bleed
Starter clutch consideration
I think the jets can be numbered differently if they are Mikuni jets versus another brand. I saw something of this in a Venture Mikuni carb rebuild video but I couldn't find the correct place in the video just now where that was discussed. Mikuni jets have a ring around them.
On another bike ,my gsx 250 I had it tuned to perfection but today started spluttering. Carbs off , petcock cleaned ... Fuel filter off but when I was conked out on road I noticed a kinked fuel pipe.
Now this is the same pipe as I have used on 750 http://www.specs-by-post.com am now convinced I messed up cutting it too long (making it prone to kinking ), buying a length too soft for the bends and when used with my filter is prone to kink.
New fuel lines ordered that are firmer.
Might at least be one of the contributing issues.
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