Newbie and help needed

Hi ,

This is my first post and I'd like to thank everyone in here as ive been reading many threads and found some geat info out and had lots of laughs along the way,:smile::biggrin:

sorry to continue an age old thread but this is really buggin me about my bike.. and I'm trying to solve it before handing in to the stealership along with my hard earned cash to try and solve it for me. I never bought the bike for fuel economy but its far worse than I ever thought it would be. I used to have a 3rd gen 750 and it was much better on fuel than my new one. Im no mechanic but I took apart quite a bit of my 3rd gen and cleaned it etc before selling so am confident on most basic jobs.. I'm just about to to a brake overhaul on the new beast so also any tips on the bleeding procedure on linked brakes would be good,, I've got the manual and it looks slightly complicated

So onto my main issue....
:frown:
1998 5th gen, completely stock, 50,000 miles, full service history, living in the colder UK climate, Rider 6ft 3inches tall, weighing around 15 stone

Im averaging 28MPG, never much over 30? I get around 130 miles to a tank, even if I ride like a granny i only see 140 miles. If I play hard then I'm lucky to see 90 miles to a tank..

Ive read many threads about this but am still a little confused? I'm gonna try giving it a service, oil, filter, sparks/ air filter see if that helps... Any other suggestions or same problem that was solved by someone? I read on here someone disconnected the battery and it reset something and solved it,, I tried that but no better ,, last fill up was 16litres and i got 98miles :frown:

oh my daily commute consits of approx 40 miles of city and highway riding. , mostly highway at around 90 and then a few miles of city filtering through traffic..

Thanks,

 

Thanks for speedy response.

exhaust is stock, and as far as i'm aware so is ECU.

Don't even know what vacum lines are? lol, but if their easy to get to I'l av a look,

It seems to run fine, exhaust is maybe blowing a little, smells normal too? doesnt smellof clean air back there ,, but like a motorbike,, lol as|I said I aint no mechanic,, just trying to learn how to look after my baby :tongue:

 

Check for tires pressure, Air filter, Spark plugs. Adjust your iddle to around 1200. Other than that the bike should get at least 35MPG

 

Do you run with big saddlebags?

 

What engine temp does it run at highway speed? Possible thermostat issue?Should run around 174-178 at the coldest after at temp.

 

On the brake bleeding issue, it's a royal pain in the arse, at least it was on my 6th gen. That being said, take your time, read the manual very carefully and follow Honda's instructions word for word. Even if unbolting calipers, turning them different directions, hopping on one foot and quacking like a duck, may seem silly, it's needed to complete the job with no air in the system. Also, a vacuum bleeder will help alot and save you some time and a lot of mess to clean up. Once again, that being said, if you use a vacuum bleeder you will first need to remove all the bleeder screws completely and wrap some teflon tape (white stuff used for plumbing, found at any hardware store for a dollar or less) around the threads to seal them up and make the vacuum suck mostly brake fluid instead of mostly air past the threads. Good luck with all the fuel mileage issues, might just need new plugs and a re-sync if ya get lucky!

 

Nope, No saddle bags

 

Being in the UK, I think mine displays in Celcius and is between 63-72 depending on run.... ,, 72C is only 161F so this could be my problem? may have made a breakthrough.. I usually have it set on ambient air temp but Im just about to go out on it to work so will get a more accurate reading and post it asap..

Thanks for your time,

 

ARRRGHHH THE BRAKES!!!!!! LOL,

Im doing them this wedensday with a mate who works for a car brake garage. Hes never done bikes before, but with the manual Im hoping he should manage it.. Is it right you have to lift the tank to bleed the system properly? I guess i could check my pluggs and air filter while there..

Thanks for the advice,

 

Evil, Toe Cutter beat me to the punch here and you've answered the question that confirms your problems assuming the temps you state are correct. You have a thermostat that is stuck open. Even when riding in sub-freezing temperatures, it should never dip below 167F-169F (75C-76.1C). What happens here is that the ECU is trying to get the engine up to operating temperature (77C-78C). It does this by making the air/fuel ratio richer. When the thermostat sticks open whether it be partially or fully stuck, the cooling system prevents the bike from ever reaching operating temperature and thus the ECU is always making the fuel mixture extremely rich. This is quite a common issue on 5th/6th generation VFRs.

Somewhere around here on the forums is a link for the service manual and there are also several how to threads with pictures. The job is a royal pain in the ass to do because you have to take off the airbox and throttle body assembly to get to the thermostat housing buried underneath. It isn't a difficult job to do any just about anyone is capable of doing it so long as they take their time and pay attention to what you are doing. Nothing special is really required to do the job other than a long phillips screwdriver and a home made tool to make sure that the throttle bodies are tightened down to the correct specs which can be made out of an aluminum can.

Just a little bit of advise here... When you go to replace this, make sure that you test the new one BEFORE you install it so that you don't have to go through the whole ordeal all over again. A simple thermometer and a pot ofwater on the stove will suffice to test with. Just hang the thermostat in the pot of water so that it isn't touching the bottom and slowly bring the water up to boiling temperature. The service manual specifies the exact temperatures that the thermostat should begin to open as well as be fully open.

 

What do you use the aluminum can for, checking the gap on the throttle body clamps????

 

I can confirm running temp. On way to work air temp was 12c and on highway doing 80mph engine temp was 69c. In the city at lights it rose to 73c.On way home at night 7c air temp, engine was 62c on highway. So we can confirm bad temp sensor then? Thanks

 

Correct. You can cut out what you need with the correct gap on the end (I think it is 7mm). The flexibility of the aluminum can lets you maneuver it in there quite easily and it is just something that is readily available and easy to use... All of us either drink a pop or beer from time to time.

This wouldn't be a bad temperature sensor, but a faulty thermostat being stuck open and needing replacement. I'm sure that if you let it idle long enough without riding it, you will find that the temp will eventually climb above 100C and the fan will properly kick on at 105C-106C. If your fan kicks on at the proper temperature I would say that it is reading correctly. The thermostat is a very very common issue with the 5th/6th generation VFRs and poor fuel economy is almost always a sign of a stuck open thermostat. Your temperature of 69C comes out the 156F, which is exactly the same temperature my VFR was running at when I experienced the exact same issues that you are having. A new thermostat solved everything.

 

Thanks meat loaf. I'l get it done asap and post the results. Think i'l leave the fitting to honda , looks too complicated for me. You guy's saved me £40 per is diagnostics though so i. Gratefull for that. Thanks again

 

Glad to help

 

Just an update,,,

SO I've not yet got round to replacing thermostat, not changed plugs and filters either but I did run this through it.. STP Fuel & Oil Additives - Choose The Best Fuel Additive For Your Car

Before now ive been averaging 120-130 miles to a tank which is around 29MPG until I put this stuff in in,, Now Im seeing 160 miles to a tank which is around 35MPG.. Also the bike is a little more responsive, seems to be a little faster on acceleration but strangley it sounds better!! got more of a rasp to it.. don;t quite get that , maybe the engine is just lettin me know its happier

So I cn highly recomend this stuff, or something similar if like me you got an older machine [ 1998, 54,000 miles on clock ]

I'l update when I get the cash to replace thermostat and do full service..
bye for now!

 

Stack me up with you, My gen 5 only gets to 160-165F on the highway, has black plugs and gets about 30-32 MPG just over 7L/100K, with a 250K range. the rads get warm very soon after start up which I'm told is another sign of T-stat issues as well as it seems unduely affected by ambiant air temp changes. It's not bad but could be better I think. 10 years old 14,000K and a known problem... My stuff is on order.

 

Squamish, you're correct. I'm sure that you will find it partially stuck at least when you take it out. Be sure to test your new one before you drop it in. It's a shitty procedure to do once, let alone twice for a bad part out of the box.

 

Hi all,,

Just an update,, So I FINALLY got the thermostat replace.... dont ask.. been traveling around the world alot... and Im pleased to say the temp is now reading 76C even gets to the 80's and then 100 in standstill,, I heard the fan for the first time the other day,, so that defo confirms whet you guys were saying..

Gotto thank you so much to the ones who replied to my questions,, we vfr owners owe alot to you guys!!
:kc10: