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Discussion Starter · #1 ·
Honda XRV

Hi everyone Merry Christmas.

This is a long descriptive post of the issues I am having - sorry but I cant find a short way to do it.

Myself and my fiancé are traveling on our 93’ Africa Twin and I am getting some pretty heavy engine trouble. Our current location is Panama.

1993 XRV750 RD07
Bought at 38,000km
Carb rebuilt @ 40000km (Carb was heavily corroded inside - rebuilt with new parts and sonically cleaned.)
Milage - 64500km

After riding over the Panama Canal a day or 2 ago - I was stuck in really heavy slow traffic that was slightly faster than stop go. This meant that I was in 1st & 2nd gear for 2 hours modulating the clutch pretty much with out a rest, just creeping along for 2 hours.

We stopped for dinner and then trouble started. When i went to start the bike the Tripomiter was reset and the bike would not start as if the battery had died. It fired up after a while but had run rough ever since.

Currently the bike idles OK - but I have had to turn up the idle adjuster knob to keep it at 1250rpm idle. Sometimes on idle the bike revs raise up to 2500 on their own and then drop back to 1100rpm. Sometimes the revs just die and the engine dies.

Some times it starts right up - other times it turns over and i need to use the choke and throttle even when the engine is warm to start again.

When riding in I am getting heavy and erratic engine flat spots and throttle surging. It is not consistent and seems to change depending on how I use the throttle.

Some time these flat spots are at low revs - sometimes they are at high revs. Sometimes giving if a lot of throttle helps it to blast past the flat spots and some times it just Boggs down and gets stuck at say 5000 rpm.Some times gently building the throttle helps to ease its way up the rev range and gently build over the flat spots.

Generally the bike still runs OK around 100kmph in 4th / 5th gear between 3500 & 4500rpm. But I feel like I am getting a lot of vibration above 3500rpm - like a hammering sensation.

Something that really concerned me was a big knock that I have had twice when starting the engine since these troubles have started. First time (cold start) it just sounded like a dull and solid thud upon pressing the starter button. Second time (Warm start cooled for 1 hr after highway riding) I felt engine movement and then what I think was a larger thud.

Both times after this the bike would not turn over at all like the starter worked but was being restricted - the starter sounded similar to when the battery would be dead (but this was not the case). Each time I stuck the bike in gear and rocked it then it started up with different degrees of throttle coercion.

I think the valve seals have been going out for the last 2000km as I get light brown smoke on deceleration.

Since this trouble started there have been bouts of blue smoke on acceleration that clears.

I fell like the afore mentioned clunk could be a stuck valve that the piston hit upon starting?

So far I have……..

1. Cleared out the fuel tank and drained the carbs to remove any water that might have been there.
2. Cleaned the K&N filter - (It was cake with dirt the front side of the filter, dirty everywhere else.)
3. I checked and cleaned the spark plugs (12000km on plugs) I am getting good spark on tick over. Plugs in the front cylinder brown, plugs in the rear cylinder black & sooty.
4. Reconnected the breather tubes - (I realized the breather pipes have not been connected for the last 3000km)
5. Tightened the exhaust mount on the rear cylinder,
6. Tried to better fit the boot from the air box to the carb on the rear cylinder ( I just can’t get it all the way down to the face where the screws are).
7. Fuel filer has been on the bike since I bought it @ 38,000km - so yes that needs changing. (I have not done this yet)

I will most likely do the work my self, I have a reasonable set of tools and will find access to a shop here. I also have the Haynes manual.

Things I am considering to remedy the problems.

A) - Fuel additives and Carb cleaner to clean out the carb and valves.
B) - Open the carb and clean - I do not have a rebuild kit.
C) - Engine out and rebuild the heads - I have a seal kit and valve stem seals, but no valves or guides.
D) - Check electronic components - I can borrow a multi meter.
E) - Replace electronic components - I do not have any of these available.

Parts take a long time to get here unless I get lucky with other bikes available in the country. So if I make an order I need to get it right first time.

If you have gotten this far a HUGE Thanks in advanced for taking time to read this. An even bigger thank you if you are able to offer any advice or have experienced a similar problem and are willing to take the time to reply.

A little disclaimer - To clarify in case anyone feels like that traveling at this time is irresponsible due to Covid. We began our travels in late 2019 and shipped our bike to South America in January 2020. We have strongly considered ending our travels. However the details of our situation mean that we have had no option but to wait things out since early 2020, primarily this is because we are 2 different nationalities (Which means that we could not return to the same home country).
 

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Sorry to hear of your problems and good luck! The only obvious common problem not mentioned is to disconnect the choke from the carbs. They need the plunger with spring put back in the carb body and a blanking screw fitted (the blanking screw fitted on the brake calipers fit perfectly for this job). I would change out the fuel pump and fuel filter as well.
 

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Check the charging system and state of battery. As Barftone as said check the chokes. Take the plugs it if they are black very likely sticking chokes. Hope its nothing serious. Good luck
 

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Discussion Starter · #4 ·
OK - I found the rather large problem and I think it is quite out of left field……..

The crank case is full and I mean FULL of fuel. My estimation is 3 liters of fuel (6 liters came out and a 1/2 liter went all over the floor due to the pressure). I found this out at 9pm just before wrapping up after a day of cleaning earths , connections and plumping a new fuel filter and line.

Off to bed now - I will be having a conversation with my motorcycle mechanic friend I made in Bogota tomorrow when I am all rested.

For tonight I drained the 50/50 Oil Fuel mixture out of the Engine, pumped a few mm of fresh oil in the cylinders and turned over once by hand. Engine still turns over freely.

My mind is racing with wondering just how long it has been running with a sizable volume of oil in the fuel. If I equate it back to when trouble started then around 100km almost all at Highway riding. Or maybe it all drained in during the last night??? The mix was heavier oil at the bottom and more pure fuel at the top. Considering how much it would have mixed in a running engine - would this be expected to have separated during a 24 hour period? OR is there separation because fuel has dripped in on top over night?? I will keep an eye on the bottles of drained 50/50 mixture to see how quickly it separates, perhaps this will give me some insight.

In any case after turning the engine I am confident that there is not overly significant damage - though of course bearing surfaces will have been effected to some degree.

Late night messages from my Bogota mechanic (Gustavo)

“The seats in the carbs are not closing.” - “ The needle that pushes the floats.” - “Not to worry you didn’t use it that much (since the problem)”

TOMORROW IS ANOTHER DAY & most likely a Carb rebuild.
 

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Hopefully you have found the problem, I always thought the excess fuel vented through the overflow pipe? Good luck let us know what you find.
 

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Previous owner of my 1995 AT said that when he rebuilt it, he started the engine using a small fuel container suspended from his garage roof, and a long pipe to the carbs. This worked well, but when he stopped the engine, he noticed fuel was flowing onto the floor from the overflow pipes as stated by @een705 above. Apparently, the head of pressure from the raised fuel container was enough to overpower the float valve springs. So, the overflow pipes did their job there. In your case, maybe they are gummed up with crud? Not the source of your problem I know, but worth checking anyway. It might be relevant that fuel didn’t overflow when the engine was running, so your crankcases may have filled up only while the bike was standing.
Good luck with sorting it.
 

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The fuel getting into the engine sounds like an issue I've had with my Suzuki xf650 Freewind. The vacuum fuel tap somehow stayed open after I switched the engine off. A well later when I attempted to start it, it failed so I took my Transalp instead. On returning home I found a puddle of oil under the engine, the engine full to the top with fuel oil mix and on further inspection fuel in the airbox. I've no idea off why the vents didn't work but fuel went through carbs into airbox and engine. It does happen. I've now installed an inline fuel tap that I turn off and on to prevent this happening again.
 

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Discussion Starter · #8 · (Edited)
December 27th’s mornings unsent post.

Good morning from Sunny but Stormy Aton Valley. Thanks everyone for the advice. My breakfast this morning was coffee and sucking on my Carb overflow pipe. (So thanks for that - :sick:) The carb overflow pipe put up no resistance. Carb bowls made a gargling noise in both carbs independently. For now, I am putting blocked over flow pipes to one side, but not completely ruling that out for now.

I woke up bolt upright at 2am last night - MIKUNI VACUUM FUEL PUMP! - and proceeded to check the routing of the pipes (waking my fiancé up in the process).

1- Fuel IN & OUT set up correctly.
2 - Vacuum connected from carb manifold to back side center of pump.
3 - Small pipe between IN & OUT disconnected.

I had the plugs out yesterday to put oil in the cylinders, front cylinder brown and rear cylinder black soot (90km since cleaning. However when i did the last service (60,000km) the rear plug was sooty and I was running the original fuel pump up until 62000km. The vacuum pump is being pressure fed from the rear carb manifold. This is the same manifold as the block sooty plugs.

But I wondered if fuel could be sucked from the pump directly into the manifold from the Carb.

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Discussion Starter · #9 ·
OK - December 28th.

Status - carb off the bike and almost dismantled.

I am in daily calls with my mechanic Gustavo and I think we have things covered. But I want to continue this thread as I have had really good advice here from XRV750 specific advice (THANKS ALL) and also would like to try to post what the eventual solution is for the next person with 3 F****ING LITERS OF FUEL IN THIER CRANK CASE!!! :mad::mad::mad:

First thing I noticed when I removed the carb was the different colors of the intake manifolds going into the heads. Rear/Left was totally forensically clean, Front/Right had yellow deposits. Conclusion - we know that it is the Rear/Left that has been throwing fuel into the Crank case - so I can concentrate on that side during carb tear down.

Automotive tire Automotive lighting Alloy wheel Motor vehicle Automotive exhaust

Gas Automotive tire Fixture Household hardware Auto part



So referring to the exploded diagram from the Haynes manual Gustavo is pretty sure that my issue lies with (14) Float Needle Valve in the Rear/Left Carb that doesn’t close and keep pushing fuel into the carb. After breakfast I need to get just the right screw driver to take out (11) Main Jet & (13) Pilot needle so I will update later.

REAR/LEFT Carb

Product Human body Font Line Parallel



(14) Float Needle -
Did not find anything significant in terms of corrosion, debris or restricted movement. Just a little tarnishing that could be rubbed off with a finger.

(15) Pilot Screw - Heavy corrosion around Needle threads, Spring and Aluminium housing. But nothing seems to be effecting the business end of the needle.

(3) Piston Diaphragm - Damage to seal around the Choke area, (Disconnecting and blocking off the choke should solve this if it has any effect).

LEFT/FRONT Carb

Human body Font Parallel Auto part Diagram


(14) Float Needle - Did not find anything significant in terms of corrosion, debris or restricted movement. Just a little tarnishing that could be rubbed off with a finger. I could see a kind of haze where the float needle sat (but we are focusing on the REAR/LEFT)

(15) Pilot Screw -
Heavy corrosion around Needle threads, Spring and Aluminium housing. But nothing seems to be effecting the business end of the needle.

I will update this post after a full tear down.

* THOUGHT * Maybe (14) Float needle valve was temporarily stuck with a piece of dirt that became dislodged during tear down. But if not - what else could case extra fuel to flow in? Is there something in the carb that can keep fuel flowing in when I am backing off the throttle OR just throw too much in while riding??

Breakfast, tool store and then back too it.
 

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If your carbs are still assembled try filling them with fuel using a pipe to the inlet and see if you have any fuel going where it shouldn't. When I had a sticking float it came out of the overflow pipe so I wouldn't have thought it would be that. Maybe I skipped the bit but did you check the chokes by taking them out?
 

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Discussion Starter · #11 ·
Yeah chokes moved freely back and forth - Considering if they were stuck I would be riding with extra fuel going into the carb - but wouldn’t this amount of extra fuel just burn up on combustion?

Given the totally clean inlet manifold this could only be clean all over from wither being literally full like a hose of water, or, a mist much heavier than 14.7 parts air to 1 part fuel. So this leads me to believe that this extra fuel is coming in when there is air flow IE when the bike is running and not when it is stationary IE bleeding in when parked. Otherwise I would imagine that I would see a yellow tinge to the REAR/LEFT inlet manifold (same as the front) but with a line of clear at the base where fuel would be theoretically dripping when stationary. Does not rule out fuel passing when stationary, but in my mind confirms a very very rich mixture when running - and more rich than what the combustion can handle leaving residue fuel?????

OR is it just very rich on REAR LEFT causing the cleaning effect and fuel is leaking when the engine is not running??

Thanks all this thread is really helping me think it through.

Good point on the overflow however these are all clear. Considering that 3 liters of fuel has passed into the crank case surely I would have seen something coming out of the overflow pipes if that would have solved the issue of too much fuel going into the float chamber?

Thanks een705 - your making me think. I do not know enough about carbs, but I am learning a lot more in the last few days!
 

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You would not see the fuel coming out because it seems to me it went straight to the sump possibly through the inlet rubbers to the head, If it was all working correctly it would come out of the over flow pipes and onto the floor and it isnt doing that. Maybe having fuel high up in the tank somehow it was a syphon effect hence fuel going to the lowest point.
Just my thoughts?

Maybe put it back together and shut the petcock when you stop so you know fuel cant drain. I would also check the fuel pump that could be the problem my experience of fuel pumps are oem and facet pumps. 3 ltr is a lot of fuel to leak.
 

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Discussion Starter · #13 ·
Fuel for more though thanks!

well this is all about at forensically clean as I can manage.

Let the games begin!

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Just add head torch.

By the way - head torch for night time road side repairs / midnight carb builds. Fenix makes about as good a head torch as I can imagine. Bloody bright on one end - strong as hell magnet on the other. Comes in very handy.


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Just seen this thread.... it's probably too late to make a useful contribution as you seem to have matters well in hand, but I am interested to hear what the cause is confirmed as.
As a point of interest, an XJR1200 I once owned got fuel in the crankcase and spewed it out of the airbox upon starting, but this was after several months of non-use, which is clearly completely different to the issue you have (the cause being a faulty vacuum tap and one or more float valves). Good luck, and look forward to hearing the problem is resolved.
 

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Hi hope you fixed your bike and would be interesting to know what the cause was. Waiting for update...
 

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A little late to the party also.......but:
--- To check each float needle valve is seating correctly. Attach a piece of tube to the fuel inlet. With the float and needle valve assembled as if you were about to fit it to the carb, position the assembly so that the float chamber top is vertical and the float is hanging down. Now gently blow a little air in the fuel inlet tube so that you hear it going past the needle valve. Now gently push the float towards the needle valve and it should stop the air from passing if the needle valve is sealing properly. Blow a little harder to confirm this. The position where the float shuts the valve is called the float height ( check the manual) but it should hang about parallel to the float chamber top ( If you need to adjust this, gently bend the tab on the float where it contacts the end of the needle valve).
It is important that this is correct as it will affect the fueling via the jets etc. Do this with both float needles and if in any doubt, replace the needles, but repeat this check to make sure they seal for sure and the seat in the mating brass insert is ok.
Another thing that most people never check is that the floats don't have a puncture, allowing the float to fill with fuel and sink! It is unlikely, but i have come across this problem with cars before now. Just let the floats sit in a jar or such like with fuel in for a while to check they are ok.
When the bike is not running, ie at the end of the day, it is always advisable to shut the fuel tap, which you should also check that in the OFF position it also does not leak.
You may well have not done the internals of your engine any favors so once you have rectified the fuel leakage into the cylinder/ crankcase, I would strongly advise that you run the engine on FULLY Synthetic oil as it vastly superior to any Mineral oil. I used to build race engines for a living and know this all to well so don't believe anyone who says that synthetic oils are not suitable for older engines, It is !!
It is suitable and superior for all engines of any age regardless of which brand you use. BUT..... Never put it in a rebuilt (or re-ringed) engine until it is run in as the oil will prevent the piston rings from sealing with the cylinder wall ( Hence the term running in) and it will form a hard glaze which will always result in the engine burning oil.
I hope all this helps if i am not too late, but it is useful to know anyway
 
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