84 VF500F Fuel Delivery Issues?

Hi, I just joined the forum, but have read quite a few posts in the past. I appreciate all the information the community has built around these bikes!

I have owned a 84 VF500F for the past 10 years. It has always struggled to start for the first time each year. I was wondering if this could indicate issues with the fuel pump, or if this is normal? For whatever reason, if I run the starter a few times, leave it for 15 minutes it usually starts up after a few more presses. If not I give it another 15 and try again.

Other symptoms that I believe may be related to fuel deliver are sometimes the bike stutters and all power cuts out if i give it a bit of gas when its still warming up. If I take it out for a ride, stop for a bit and get back on it, it can struggle a bit to start again. I drain the float bowls every season and empty the tank. I have also followed the linked tutorial to cut the diaphragm out of the petcock in an attempt to improve fuel delivery. http://daughertymotorsports.com/howto/tankvalve/tankvalve.html however it didn't seem to make an impact.

Should i consider deleting the fuel pump? Other forum posts indicate the bike handles that well. Is this all just normal, or do you think the carbs need to be rebuilt?

 

Sorry only had fuel injected VFR's, but was just wondering, have you thought of replacing the spark plugs? Symptoms sound like old, dirty, or fouled plugs!
Just a thought.

 

If normal tune up items are current (like plugs), the carbs VERY LIKELY need to be rebuilt. Properly. The pump is not responsible for those symptoms, but you can get a copy of the service manual and test it to be sure.

How many miles total and when was the last time the valve lash was verified?

Is it stock or do you have any mods like exhaust or air box?

 

Thanks for the feedback guys! The bike is really low mileage 18500kms so 11500 miles. I did the spark plugs a few years ago and synced the carbs, however I have never rebuilt the carbs.

I did a few other things for the bike including replacing the battery with a lighter lithium iron phosphate battery, replaced the brake lines with some steel braided lines and rebuilt the brake master and slave cylinders. I put cartridge fork emulators and stiffer springs in the front, and http://daughertymotorsports.com sold me a kit to replace my rear mono shock with something more modern.

I tried to do the valve lash twice, however the engine still ticks a little. When i first did it, a few of the valves were way out. I'm wondering if its the timing chain at this point, or if the valves are a little too tight now. My father seems to think the valves may need to lapped. I'm probably going to take it back apart this winter for further investigation.

Jamie Daugterty mentioned in a previous post "Just a tip: instead of using two feeler gauges under the tappets, use a single one between the cam lobe and the rocker arm. Just reduce the thickness by 1.5 (the rocker arm ratio) to determine the correct feeler gauge to use. You can then snug the adjustment screws against the valve stems and lock them in place. Once you remove the feeler gauge you can double check the clearance at the valve if you are anal (like me). I've found this method to not require the special tools as it's easier to do."

I was thinking about testing this approach to see if i get similar numbers vs clearance on the tappets.

 

First of all, we like pictures. Pictures of cool, shiny bikes good.

Second of all, your valves do not need to be lapped (very likely) if you believe the mileage is genuine, no disrespect to your father.

Sounds like the major items have been addressed, although I would go back in at some point and recheck your valve lash (like when your carbs are out). How you want to accomplish that is up to you. Just be sure to re-check your final adjustment the normal way as a sanity check.

You didn't answer my question about the bike being stock or not regarding intake and exhaust. If stock, and air filter is in good shape, at this point continuing to chase a problem without eliminating the carbs as the culprit is a waste of time and money. If you have never done it, or have proof somebody competent did it in the near past, it is time.

Even bikes that get continued use and are properly stored when not in use can still get particulates and sediment that can partially clog jets and passages. Sounds like you are mechanically inclined, but 500 carbs can be tricky little buggers, do your research and be prepared before even removing them. People can get their panties in a twist when they get called out for not having a proper game plan. With a little searching you'll see this exact scenario has come up quite a few times recently, and there's a lot of great info to be gleaned and things to avoid.

You have a copy of the HONDA FACTORY SERVICE MANUAL, right?

Post updates with pictures and ask questions. Cheers and good luck!

 

I vote carbs and new fuel filter. I would think no lapping required and stick to the standard clearance method. Buy insulators and carb kit, including fuel tube o-rings. Pics would be cool!

 

I just have a Clymer manual. The airbox and exhaust are both stock and fully intact. Its winter up here, so you guys are getting a photo in my garage. I just changed the oil in my snow blower this evening, so its a bit messy in here.



If I recall correctly, the last time I was looking at the valves I measured off the tappets setting the exhaust valves to a tight 5 thousandths of an inch, and the intakes to a tight 4 thousandths of an inch. I couldn't squeeze a feeler gauge 1 thousandths thicker in. This is my only experience working on valve lash, so maybe I made them too tight? Should I maybe back them all out 1 thousandths? If it isn't the valves, is there anything else that could be rattling around making noise in the engine? It is very hard for me to determine where the ticking is coming from, but i can hear it at idle, and a bit if i rev the engine.

It sounds like the best source for carb kits was http://billysoutback.com/ however the site is down. Does anyone have any other recommendations for a quality carb kit?

 

Others will chime in, but I always set the exhausts loose and the intake center or tighter side, as the intake seems to wear and the exhaust seems to get cruddy.

 

Pretty nice 500.

You now use the term "rattling". If you rev the motor a bit and quickly release the throttle, does the noise get louder as the rpms drop? And / or perhaps make a little more noise as it's normalizing it's idle after a rev?

This really sounds like your cam chain tensioners are allowing the chains to make noise, usually an indication they are starting to fail. They are self adjusting, by the way. Your chains are very likely just fine, it's always the tensioners on the 500.

Get your self a copy of the Honda Manual. You can download one over on VFRD, or msg me and I can send you one.

At some point, go back in and recheck / adjust your valves, not trying to compensate for what is likely another issue.

 

I personally was starting to think it was the chain tensioner. The last time I checked the valve clearance, everything was almost 100% bang on, so I was looking for other potential issues. It does seem to continue to have a rattling sound a bit when the throttle comes down.

What do you guys think about this carb rebuild video? Do you have any other video resources you would recommend? I have rebuilt single carbs on small engines a bunch, but this is like rocket science comparatively. The process is complex, and having a reliable video would help me build some confidence in going through the motions of rebuilding the carbs.

 

Matt is a member here, and he quickly became pretty damn proficient on things "500". Good vid. Head over to V4Dreams and read his tutorial too. It is on a set of later VFR carbs, but the principles and things to address are similar.

Between that vid, the Factory Manual, and a tutorial or two, it is a good foundation. I'm sure there are a couple other great vids somebody will link too. Search "carb rebuild 500" on this site (upper right spy glass) and check the "Search titles only" box. LOTS of info, and you can learn from other's mistakes.

First piece of advice: CARBS COME OUT AS ONE UNIT WITH THE TOP PLENUM STILL IN PLACE

 

I take photos of the carbs before I pull them apart to see where hoses and linkage were routed originally. Marking my carbs (1/2/3/4) before removal several times helps me a lot as well. Once I pull them apart it takes a bit to wrap my head around which one went were if I lose the markings.

The video is good and we can answer most questions if you have photos attached.

Always remove and install as a set (plenum on) and purchase the insulators if they are the original. This will save you so much time and effort. You know, what Capt just mentioned. hahahaha

You got this!

 

Awesome. I'll start planning a carb rebuild. Sorry I'm jumping all over the place in this thread, but does anyone have any links to a video of a cam chain tensioner replacement on a vf500f or magna maybe? I can't seem to find any video tutorials on the subject.

 

Read your newly sourced FSM. I just approved your request.

 

Thank you Captain 80s. The manual is much better than my Clymer.

 

Thanks again for sharing the manual. I could use a bit more advice on the subject of inspecting and potentially replacing the cam chain tensioner.

Under Cylinder Head and Valve Covers section I see the process for removing and inspecting the cam chain tensioner. The manual shows the cam sprockets and shafts out of the engine though. It is included in a sub section related to removing cylinder heads. Is removing all this required to inspect and potentially replace the cam chain tensioner?

The section related to cam Chain guide and cam chain tensioner inspection shows the cam chain tensioner assembly out of the engine. It says to "Inspect the cam chain tensioner slipper for damage or excessive wear. Inspect the spring for good tension." It is unclear to me what good tension would look or feel like as there is no method to measure this referenced in the manual. With this in mind, I would probably air on the side of caution and just replace both cam chain tensioners if I go through this process.

 

Basically, you need to create enough slack to remove the tensioner. It's been a minute since I've done this job, but usually removing one camshaft is sufficient.

Sometimes the unit is just plain worn out. Sometimes the shaft that attaches to the runner that is applying tension is bent or damaged and can't move freely. Sometimes the one-way locking mechanism is worn and doesn't "hold" the shaft anymore. You might be able to visually confirm something bent. But if I was going thru the process of removing one to inspect, a known good unit would 100% be going back in. Whether that is new one or one out a super low mile engine that had other issues.

 

Hi Captain 80s. Thank you, you have been extremely helpful.

 

Good luck finding a new tensioner.

Sometimes you can cut back the sleeve that covers the spring if its pinched and get more tension, or do the mod and move the spring angle.

Carb sync can also make a big difference in how the engine sounds.

Here's a link to the tensioner mod if you decide to dig in

https://v4musclebike.com/forums/showthread.php?t=1732

Sent from my SM-S911U using Tapatalk

 

i wouldnt take anything apart until you have good replcement parts in hand.