Loss of power(speed) @ Hwy speeds...

[Anonymous]

Hi,
I was driving home from work going (65-75) and the bike started to lose speed. Gradually went down to 50-55 @ full throttle. Now the bike is responsive upto 50 or so but after that the throttle has little effect. When I do
try to go hwy speeds the engine kind of gets this bogging sound, BlAHhhhhh.
One more thing, if it starts to slow down in 5th and I kick it into 4th I can get more rpm and go faster...? 1985 GS300L Twin

Good day,
intercessor

[focus frenzy]

obstruction blocking fuel flow, possible clogged inline fuel filter, clogged fuel screen in tank, clogged screens on the needle valve seats.

clogged fuel tank vent allowing a vacume to build up in the fuel tank.

[ccratin]

Are both of the cylinders firing? I've had trouble recently with my 450 and it certainly has trouble going past about 45 on one cylinder. Take a look at your plugs to see if you are fouling one. On my, the petcock was leaking causing gas fouling on the #2 cylinder . . . easily visible on the plugs. Also, check the plugs to see if you are getting a good fat spark.

[Anonymous]

It seems to be firing on two cylinders. I guess I have a lot of items to check.

intercessor

[ToddB3]

check your compression if the above checks look good, I had the same symptoms on an older bike one time and did my checks and realized the bike was using a lot of oil,(I didnt know much about bikes at the time and I was 250 miles from home) turned out that I killed some old piston rings trying to keep up with a friend on a newer bike on a 300mile ride. I did make it home but doing 30mph at full throttle!

[Anonymous]

This bike runs good upuntil 45+ not sure it would be the compression, but I know some with a compression meter.

[maparker]

Two thoughts on this: First you may have a clog somewhere in the main jet circuit. I believe this controls things above 3/4 throttle?

Second, I had similar problems, bike ran fine at lower speeds, really try to get it up there and it would just bog down. One reason I let the bike sit as long as it did is because I got stuck on the interstate and couldn't get it above 50 8O Ever been passed by a semi running 80? Turned out my R/R was the culprit. The battery would run the bike fine at lower speeds, but just couldn't keep up with the demand to push the bike faster. Check your voltage across the battery and see if you are charging correctly. If not it may be time to do some 'baywatching for a Honda R/R.

Good luck,
Mark

[Anonymous]

Interesting, I did check my voltages awhile back, they seemed fine. Except that I dont have a tach so I have no idea what rpm I was at. I was having other problems (which are in another thread, basically the bike would sputter at low speed acceleration) until I put in a new battery. The bike proceeded to run the best it has ever run. Then 1000 miles later this stuff...

intercessor

[maparker]

hmmm... Sounds more and more like the situation I had. The bike didn't run that great, new battery and things were cherry. Next thing I know I'm having all kinds of problems again. If I were you I'd at least stick a voltmeter across the battery and see what you get. However, if your battery is shot you may not be able to get accurate readings....

IMHO its worth dropping in a Honda R/R anyway. Even if your stock one is OK now, consider it preventitve maintanence 8)

[Anonymous]

Curious as to why you are recommending a Honda R\R?

Thank You

[maparker]

Over the stock? Larger heat sink which makes it more efficient/less prone to failure. The stock unit only regulates two-phases sending the third to the headlight circuit, bad design in most peoples opinion. The Honda on the other hand regulates all three phases making it less likely that you will cook your stator. Important consideration since a new stator runs in the hundreds of dollars....especially since many of us picked these bikes up for much less The Honda is often specified simply because you can often make the holes line up and mount it in the stock location. Also you can often pick one up off ebay mucho cheap, or try your local bike wrecking yard. I got mine delivered for <$20. Take a look at some of the following threads:

http://www.thegsresources.com/_forum/viewtopic.php?t=36169&start=0&postdays=0&postorder=asc&highlight=honda+regulator+mod

http://www.thegsresources.com/_forum/viewtopic.php?t=37819&postdays=0&postorder=asc&highlight=honda+regulator&start=15

http://www.thegsresources.com/_forum/viewtopic.php?t=33867&highlight=sh232

[Anonymous]

Just wondering what types of problems you had before the RR replacement?

Good Day
intercessor

1985 GS300L 14k

[maparker]

Sorry for the late repy, I was on vacation I was having trouble with the bike having any power at highway speeds. No matter how much you twisted the throttle you couldn't get it over 55 or so (Its been a couple of years so my memory is a little vague). Seems like it ran fine with a fresh battery around town, but I couldn't trust it on the highway. Seems like it also blew my headlight? but again its been a couple of years... There are tests you can do to see if your stator and R/R are OK. The easiest being to test your voltage at the battery. Not saying that this is your problem, just that its a possibility.