'82 Seca 750 Refresh Project: Now Scooby's Bike

USE A GREASE GUN

 

Popped it out with a hand air pump so I wasn't blasting air in there. Grease gun also works great. Not sure why it got stuck. I just rebuilt it, new parts and sanded the bore. Though it the piston was sitting in there for a few weeks until I finally put some brake fluid in the reservoir to test it. Whatever the case, gonna re-sand the bore and use some of that rubber to metal grease.

 

How do I bench pressurize the master cylinder? The one I rebuilt doesn't really seem to pressurize too well. When it's empty and I put a finger over the output hole, I can hear air being sucked in through the reservoir. When I fill up the res I never get any pressure on the pivot. If there is any pressure build up, it's miniscule.

I have a second master cylinder I bought off ebay for cheap. It hasn't been cleaned or rebuilt and is quite dirty, yet the pressure builds MUCH better than the one I rebuilt.

 

Did you fit the seals the right way round on your rebuilt master cylinder?

 

"Sand the bore"
Why? Do you think yamaha made it too small?

 

Here's a side by side with OEM (Bottom in pic) and Aftermarket (Top in pic). My MC has little to no pressure after I installed Aftermarket seals. I bought a used MC for the bike from ebay to make learn more how the MC works and to swap parts. At first I thought it was an MC problem but I swapped the OEM seals with the Aftermarket seals in my MC and it builds pressure great. So it's a seal problem. Gonna swap some parts to see if it's the spring seal or the piston seal.

 

I watched a video on a thread here by Moto Stuff and he sanded the bore a bit with a 1500. Honing would be best but I don't have one.

 

You should drop the piston into the bore without the seals in to test the fit. Unless you have corrosion no need to "sand" anything.
Did you run your engine until the smoke cleared yet?

 

So I ran a few pressure tests swapping out parts. Seems like the Aftermarket spring seal is the issue. Aftermarket piston and seal are good. MC is good. Bore is clean. Everything fits. Gonna see if I can get a new one.

I haven't started the bike yet because I brought the fuel tank to be glass bead blasted so I can repaint it myself. There's only two motorcycle shops by me. Because I do all my own work except for some things that I don't have the tools for, I bring in small parts to work on at the shop and I think they put my parts LAST on their big list of repairs.... why do a 50 buck job when you can do the 1000 dollar jobs first? So I'm waiting until they call me or I bug them that it's been three weeks now...

 

I fixed the brakes. So I'm back to working on getting the bike to run. Unfortunately, the owner of the bike shop I was going to have the fuel tank glass beaded had died this weekend so I have to find another location to make the tank have a nice bare metal look so I can repaint it.

I have, however, got a nice aux tank setup so I could work synching carbs. About 20 seconds later and the starter motor is no longer turning. There's no clicking sound. Hitting the "start" button doesn't do anything. I didn't completely rebuild the starter. Any ideas? Otherwise I'm going to pull it, test it. Could it be pulled without draining the engine oil?

 

Yes you can remove the starter motor without draining the oil. Try jumping the solenoid contacts first to see if starter operates before removing the starter motor. You could try a car battery too and jump leads in case your bike battery has a low charge. Your bike looks great.

 

I guess no then, poo, looking forward to a big YEESSS from you after all this hard work...

 

I just fixed the starter motor today. So another attempt at synching carbs. Tomorrow I'll try to get the engine started again and take a quick video.

 

Had a small break from work so I decided to start up the engine. See how it is. Cylinder 3 doesn't seem to be firing. Stalls out when I pull off choke. Stalls out when I blip the throttle. No more white smoke so it must've been when I added oil into the cylinders. I was working quick so I think I turned off choke too early or I tried adjusting the mixture screws while on choke. Mixture screws turned out three turns. Any ideas? Gonna try more this weekend.

 

The video doesn't tell me much, other than you are trying to run a cold engine without enrichner - you can't, well not if the idle jets are correct and mixture screws set close to right.
Warm it up on choke and throttle before adjusting anything. And the white smoke gone? - I told you so.

 

Been adjusting the mixture screws. Turned them out to around 3 1/4. Starts up on fully open choke. Revs up to maybe 2k. I let it sit around there for about 30 seconds. Occasionally I hear some pops but not a whole lot compared to when I first got the bike. The RPMs also don't fluctuate wildly. I tried to ween off choke but it slowly dies out and will stall if no choke is pulled.

I gave a little tiny blip of the throttle and it shot up to 7k RPM and had a bit of an issue coming back down at a steady rate.

Cylinder 3 seems to firing.. but only occasionally? I'm not sure. The pipe isn't cold. But it definitely isn't hot like the other pipes. You can put your hand on the 3 cylinder exhaust and hold it there with no issue. I plugged the vacuum line with a plug from autozone. It could be that it's not plugged up fully or the spark plug is fouled. I'm gonna check those. I think before I do anything. I should make sure cylinder 3 is firing alongside the others.

If choke has to be fully open, even after the bike is warmed up then it should mean the current mixture with choke off is too lean right? I don't know if I can turn the screws out more than 3 1/2

 

Got the bike to run without choke. One of the spark plugs wasn't firing so I just replaced all of them. It holds an idle around 1400-1600 rpm. Sometimes the rpms randomly shoot up to 2 or 3k when I start up the bike. Blipping the throttle makes the rpms hang high around 2k and slowly come down. Not really sure what's going on there. But I don't know which screw I should adjust. The idle screw sitting in the middle of the carbs or the mixture screws to fix these random rpm spikes or the hanging rpm when throttle is blipped.

 

The idle screw in the middle is the idle speed screw. The ones on the carbs are mixture, and if you don't have any other way to set them adust each one for fastest idle - the idle speed screw is tweeked in between. But, it sounds like you need a vacuum synch first - this sets all the butterflies to the same position, and is vital to get it right.

 

I got the idle to sit around 1050 with the idle screw. Getting ready to check vacuum synch and color tune the carbs. With that whole blanking tool for YICS engines. I read mixed thoughts on it but I guess I'll just follow the book.

I was looking at a thread about clutch adjustment and saw I might have set my clutch lever arm wrong. The two lines were lined up before I got rid of free play. So without free play, the line on the lever passed the clutch cover line. So I moved the lever arm so that the two lines match up without any free play left until you need the mechanical advantage of the cable to disengage the clutch.

But now I can't get the knurled part of the clutch cable to reach that little clutch hook so I'm not able to adjust the clutch. Am I doing something wrong?

 

Fooling around with the clutch again and I lined up the marks as best as I could. It's about one spline off. I'm not sure if this is OK or not because the cable simply cannot reach or the lever needs to be pulled in more. Right now it's completely stopped with just using fingers. Pliers would be needed to pull it over more But then the lever would always be under tension.

With some adjustments I'm able to get 3mm freeplay at the handle bar lever. Starting up the bike and shifting into first, the back wheel rotates even when the lever is pulled completely in. So it must not be fully disengaged.