'83 TCI question

[pa23driver]

Hi all,

Been a while since i've logged on, glad to see the place still kicking.

Recently picked up a 1983 special for a steal (i'll post pics if anyone cares), not running - of course. Decided it would make a good project for me and the old man to tackle.

Before we get into throwing a lot of money into the thing we'd like to hear it run but can't get it to spark. Bought a brand new coil (Mikes ultimate high output Part #17-6903), opened the TCI case to find everything in pristine shape, and checked the ohms on all the diodes which checked well within range. even checked the resistance in all the leads (all seven) which were all fine.

It also doesn't spark when the kill switch is flipped off, which is odd. any ideas?

Side question: who carries genuine mikuni floats and valves for the BS34?

 

[hmusket]

'82 and '83 models had the extra safety features, sidestand and clutch relays. Check those out.

 

[nj1639]

'83 should have the plastic floats. Are they leaking? It's been some time but I got float needle valves through Mikesxs- and do watch out for the extra safety features like hmusket sez, I removed mine.

Post some pics....

 

[xjwmx]

^ my needle for his year from Mike's expanded its rubber tip until it got stuck in the seat. I would go with genuine Mikuni but I don't know where to get. Would like an answer to that myself.

Regarding ignition, be sure to check the pickup coil with a meter. If I remember right you should see about 700 ohms from grey and orange to black. Bad pickup coil means no spark or erratic spark.

 

[aldo5468]

Does it have the original fuse block with 4 glass cartridge-style fuses? The fuse holder clips in these weaken and are prone to breakage - many folks replace them with modern ones; others replace the clips and continue using the old-style fuses. Either way, this is a notorious weak point in these old 650's, and must be addressed to help ensure electrical reliability.

 

[jetmechmarty]

Side question: who carries genuine mikuni floats and valves for the BS34?

Sirius Consolidated has floats. This at $9.

Another at $26.50.

It makes me wonder if one of them isn't genuine Mikuni. Look into it.

 

[pa23driver]

some pics...

not a bad stocker for 300 bux, assuming we can get it to run.

I'll check out the pickup coil and make sure the safety stuff is bypassed. the glass fuses have been removed and replaced with a blade type fuse block.

 

[xjwmx]

It makes me wonder if one of them isn't genuine Mikuni. Look into it.

I don't think so because that site also has this:


Name YAMAHA GENUINE MIKUNI CARB FLOAT Part No. N133211 Model SEE DETAILS Price $ 19.99 Year SEE DETAILS Status OUT OF STOCK
YAMAHA GENUINE MIKUNI CARB FLOAT Part# N133211 Replaces OE

 

[pa23driver]

I remember reading that people had a lot of issues with the rare earth magnets on the rotor. Should those magnets have a pretty decent pull to them? the ones on the bike seem kind of weak...

 

[xjwmx]

^I think the symptom in those cases has been limited revs, not "no spark".

 

[pa23driver]

^I think the symptom in those cases has been limited revs, not "no spark".

I'll keep that in mind. Ohms checked good on the pickup coil, getting chilly out there tonight, so i'll get around to checking the saftey stuff tomorrow.

 

[jetmechmarty]

I don't think so because that site also has this:


Name YAMAHA GENUINE MIKUNI CARB FLOAT Part No. N133211 Model SEE DETAILS Price $ 19.99 Year SEE DETAILS Status OUT OF STOCK
YAMAHA GENUINE MIKUNI CARB FLOAT Part# N133211 Replaces OE

Three options! I wonder what a $26 float has that a $10 float doesn't have. FWIW, my experience with parts from there has been very good, so far.

 

[jetmechmarty]

some pics...

not a bad stocker for 300 bux, assuming we can get it to run.

I'll check out the pickup coil and make sure the safety stuff is bypassed. the glass fuses have been removed and replaced with a blade type fuse block.

WOW! It even has the elusive lower left side cover! Does it have the right one too? That's a purdy ride.

There is a two wire connector under the left side cover that goes to the side stand safety switch. Disconnect it and jumper the plug. If that switch is bad, the bike will now run.

 

[xjwmx]

I think I'm seeing this. In the expensive float notice a bushing where the pin goes that isn't there in the cheapest one. 5twins says that Mike's doesn't have the bushing, which makes it not work very well. The Mikuni has the bushing too.


On the Mikuni seats in my carbs there's a microscopic number which I think relates to the hole size, as with a regular jet, but I've never recorded it. That number might help with tracking down a new Mikuni seat and needle.

 

[pa23driver]

WOW! It even has the elusive lower left side cover! Does it have the right one too? That's a purdy ride.

There is a two wire connector under the left side cover that goes to the side stand safety switch. Disconnect it and jumper the plug. If that switch is bad, the bike will now run.

It actually has both lower side covers, they're in rough shape but nothing a little fiberglass/jbweld can't fix.

thanks for the tip, i'll give it a shot later today

 

[pa23driver]

I think I'm seeing this. In the expensive float notice a bushing where the pin goes that isn't there in the cheapest one. 5twins says that Mike's doesn't have the bushing, which makes it not work very well. The Mikuni has the bushing too.


On the Mikuni seats in my carbs there's a microscopic number which I think relates to the hole size, as with a regular jet, but I've never recorded it. That number might help with tracking down a new Mikuni seat and needle.

I'll have a look at the seats and see if the number is there. Not sure if the carbs need new floats and/or seats, but they're flooding like crazy when fuel is turned on, so they're getting tore down and gone through.

I'll have a look at the OEM seats from my '77D, i'm curious to see if they have a number as well.

 

[gggGary]

Those float valves normally clean up fine, VERY often the issue is the o-ring is brittle and allowing gas to bypass the valve.

A typical as removed valve body with brittle o-ring

On the spark if the rotor has been replaced the magnet may not be the correct distance from the pick up (too far away). But I agree it should spark once on power off.

 

[pamcopete]

WOW! It even has the elusive lower left side cover! Does it have the right one too? That's a purdy ride.

There is a two wire connector under the left side cover that goes to the side stand safety switch. Disconnect it and jumper the plug. If that switch is bad, the bike will now run.

Not necessary to jumper anything. Just pull the side stand safety relay.

 

[XSLeo]

I might try using a jumper wire from the battery positive to the red/white wire at the coil. This bypasses all the switchs, relays and other crap, just leave the engine stop switch off. Don't want power feeding back through.
This should get you spark. Is so then any problems are in the wiring between the battery and coil.
If it won't spark it is in the ignition.
Leo