Various issues with my new '78 750

[beardedmonkey]

Hey all,

New guy here. I really don't have any technical know-how, but I'm looking to learn. Just bought the bike I've linked to, put about 700 miles on it in about 2 weeks of riding and I love it! I already learned about the vacum petcock the hard way (thought "PRI" meant "Primary" not "Prime" and ran out of gas). A little different from my old CBs in that respect! It does have a few issues though:

* Shifts hard, and hard to find neutral
* Trip meter (resetable odometer thing) broken (reset pin is gone)
* Hard to set idle. It's all over the place: even idling at 1500 in neutral, I'll put it in gear and the idle sometimes drops so low the oil light flickers.
* This weird thing has been happening where I'll go over a bump (I think that's the cause) and it seems like the front brake locks up. Not so much that I lurch forward, but enough to slow it down and make a weird "something stuck in the wheels" sound. A couple of folks have said they think the brakes aren't stock.
* Front and back brakes squeak/moan/make a "wha-wha-wha" sound.

Any of you located in the Eastern Massachusetts area?

Here she is: https://lh3.googleusercontent.com/-S...y%2520baby.jpg

[tkent02]

Hey all,

New guy here. I really don't have any technical know-how, but I'm looking to learn. Just bought the bike I've linked to, put about 700 miles on it in about 2 weeks of riding and I love it! I already learned about the vacum petcock the hard way (thought "PRI" meant "Primary" not "Prime" and ran out of gas). A little different from my old CBs in that respect! It does have a few issues though:

* Shifts hard, and hard to find neutral
* Trip meter (resetable odometer thing) broken (reset pin is gone)
* Hard to set idle. It's all over the place: even idling at 1500 in neutral, I'll put it in gear and the idle sometimes drops so low the oil light flickers.
* This weird thing has been happening where I'll go over a bump (I think that's the cause) and it seems like the front brake locks up. Not so much that I lurch forward, but enough to slow it down and make a weird "something stuck in the wheels" sound. A couple of folks have said they think the brakes aren't stock.
* Front and back brakes squeak/moan/make a "wha-wha-wha" sound.

Any of you located in the Eastern Massachusetts area?

Here she is: https://lh3.googleusercontent.com/-S...y%2520baby.jpg

Fix the brakes before the wheel locks up and dumps you on your head!
It is probably clogged passages in th master cylinder, the entire system needs to be disassembled and cleaned.
That looks like the stock brake but someone has drilled the disc.

The idle thing is likely an air leak, very common and easy to fix.

Might have to find a used speedometer.

The hard shifting is discussed in the other thread you started.

[beardedmonkey]

How big a deal is it to clean the brake system?

[tkent02]

Very big if you don't do it!
It takes a good part of a day, maybe more if you get stuck.
Simple taking it apart, cleaning the pieces, and putting it back together exercise.
You may need to buy a few rubber parts, and the hoses should be replaced.

[lurch12_2000]

* Shifts hard, and hard to find neutral

Adjust clutch play to proper specs, if not then it's hard to find neutral with a clutch that's not fully disengaging

* Trip meter (resetable odometer thing) broken (reset pin is gone)

who cares?

* Hard to set idle. It's all over the place: even idling at 1500 in neutral, I'll put it in gear and the idle sometimes drops so low the oil light flickers.

idle should be around 1100-1200rpm, if clutch not adjusted properly it may not be fully disengaging causing engine drag and idle drop when putting in gear

* This weird thing has been happening where I'll go over a bump (I think that's the cause) and it seems like the front brake locks up. Not so much that I lurch forward, but enough to slow it down and make a weird "something stuck in the wheels" sound. A couple of folks have said they think the brakes aren't stock.

Should check before riding anymore as others said. You don't have a centerstand because of the 4 into 1 header, but rig something up safely with a jack and blocks to lift the front wheel off the ground, then you can use 2 fingers(thumb and one finger) to spin wheel while applying and releasing the front brake, if it's dragging then pull the calipers off/apart to clean for free movement, check for 90 degree angle on brake lines to see if it's crimping as front forks compress over bumps, you can also tell if the discs are true or have high spots dragging, check to see if you have old 30 yr old brake fluid.

* Front and back brakes squeak/moan/make a "wha-wha-wha" sound.

do the same troubleshooting as front brakes with rear jacked up

BTW, I put k's of miles on my '79 GS750E...a great bike that now resides in Ohio with another forum member



Any of you located in the Eastern Massachusetts area?

many people in this area

[beardedmonkey]

I actually do have a center stand, but that only picks up the rear wheel. I'll figure out something to get the front wheel up too, and I'll see what I can find. As for the trip meter, not a huge deal, but I would like to use it to know where I'm at with my gas tank.

That's another question actually -- I've got the air pressure in my tires up to where it needs to be, and the fuel economy has picked up a bit, but I'm still only getting about 35 mpg in combined city/highway driving. Is this normal? I may be letting it sit for a while to warm up, but not that much.

[OLDENUFF]

The wha wha sound you referred to is likely because the disc's have been drilled in a straight line pattern rather than offset like the newer models.

[beardedmonkey]

So I'm stuck with the sound? Clearly there's some other stuff I can do in the meantime.

PS I love your sig -- I told my students that one and they believed me... Oh well.

[tkent02]

I've got the air pressure in my tires up to where it needs to be, and the fuel economy has picked up a bit, but I'm still only getting about 35 mpg in combined city/highway driving. Is this normal?

Not normal, there are literally dozens of adjustments all over the bike that effect mileage, and some fuels just can't give the mileage that others do.
How you ride plays into it a lot, lugging the bike makes it worse as does lightning quick acceleration and high cruise speeds. But yeah, 35 is too low for a decent 750....
Your dragging brakes could be a lot of it.

[rustybronco]

* Shifts hard, and hard to find neutral

Try chainging the oil as well as adjusting the clutch.

[cowboyup3371]

Sounds like you need to go through the top ten maintenance tasks on Basscliff's site for starters. Nice looking bike...take care of it and it will take care of you.

[beardedmonkey]

Yeah, looks like me and my buddy have some work to do... I'm assuming between my Clymer manual and this site I can figure out what to do. I love the "troubleshooting" part of the manual. Ummm... srsly?