82 Xs650 Special Float height? Info :)

notmoving

XS650 Member
Messages
25
Reaction score
11
Points
3
Location
Philadelphia
Ok thanks. So that would be 25mm, +/- 1mm, yes? I measure from the gasket placement to the top of the float, yes? If so, then my float heights are fine.

I have told I am the third owner. The first two barely rode it. There are only 20,00 miles on it! So I guess that suggests this is the original carb. How could I know for sure?

And the reason I took off the carb to clean it is a sudden loss of power. It backfired a few times when I went to start it recently and I felt a gush of air where I held the choke lever. So if the float heights are correct then what caused the loss of power. Could the gaskets need better sealing?
 
Last edited:

5twins

XS650 Guru
Top Contributor
Messages
23,454
Reaction score
19,645
Points
813
Give us some good pics of the carbs and we can probably I.D. them for you.
 

jpdevol

XS650 Guru
Top Contributor
XS650.com Supporter
Messages
1,363
Reaction score
2,869
Points
263
Location
26187
And the reason I took off the carb to clean it is a sudden loss of power. It backfired a few times when I went to start it recently and I felt a gush of air where I held the choke lever. So if the float heights are correct then what caused the loss of power.
The carb itself is seldom the cause of sudden loss of power. However, carbs getting blown off intake manifold is consistent with your description.
 

notmoving

XS650 Member
Messages
25
Reaction score
11
Points
3
Location
Philadelphia
Here ya go...
 

Attachments

  • 16620473610613011908874507371319.jpg
    16620473610613011908874507371319.jpg
    155.7 KB · Views: 11
  • 1662047384269778331282762391613.jpg
    1662047384269778331282762391613.jpg
    273 KB · Views: 9
  • 16620474221903868841830288349357.jpg
    16620474221903868841830288349357.jpg
    285.2 KB · Views: 11

jpdevol

XS650 Guru
Top Contributor
XS650.com Supporter
Messages
1,363
Reaction score
2,869
Points
263
Location
26187
I think you have a couple of threads going....

Congrats on the reassembly, if that's what we're looking at, ready for reinstall?

Before you try to start it - given backfire - probably a good idea to clean and set gap on points.

Then ya gotta synch the carbs and check the timing
 

notmoving

XS650 Member
Messages
25
Reaction score
11
Points
3
Location
Philadelphia
You're right. I didn't know the best way to get a reply. I should delete the other one but I don't see a way to do it.

Thanks for your help! Everything you just wrote - setting point gaps, synching the carbs and checking the timing - I have no idea how to do. I'm not mechanically inclined. I know how to clean and rebuild carbs - I learned that many years ago - and how to change oil but that's it. If you could walk me through it, I'd be grateful.

And should I use a gasket sealant?
 

jpdevol

XS650 Guru
Top Contributor
XS650.com Supporter
Messages
1,363
Reaction score
2,869
Points
263
Location
26187
What are we using sealant on?

A manual may be helpful regarding points. I'll see if I can find a link. But open the point (LH) cover and clean the points with folded over 600-800 grit sandpaper, spray with contact cleaner and, rotating the engine slowly by hand (rotor nut) move the small points plate to obtain a maximum opening of .014"
 

Attachments

  • POINTS CAM.png
    POINTS CAM.png
    1.1 MB · Views: 8

5twins

XS650 Guru
Top Contributor
Messages
23,454
Reaction score
19,645
Points
813
Yes, those are '78-'79 BS38s. The "tells" are no overflow hose nipples on the bottoms of the float bowls and the internal float bowl vents in the bellmouths .....

LabeledCarbMouthsSmall.jpg


Just a couple things I'll mention - are you missing the angle bracket that ties the carbs together across the bottom? Or maybe you just haven't installed it yet? .....

Finished4.jpg


Also, you have the top butterfly shaped plate installed backwards. The larger cut-out should face the rear .....

34 Alloy Tops.jpg
 

notmoving

XS650 Member
Messages
25
Reaction score
11
Points
3
Location
Philadelphia
What do I use to measure the point gaps?

I would love to learn all I can so that I can be driving a 50-year old classic Yamaha in 2029!

I'm thinking about the sealant here, but after jetmechmarty said "not ever", I looked it up and it many people agree. Nevertheless, here's a photo.
 

Attachments

  • 16620531920234858859699255023339.jpg
    16620531920234858859699255023339.jpg
    254.2 KB · Views: 9

jpdevol

XS650 Guru
Top Contributor
XS650.com Supporter
Messages
1,363
Reaction score
2,869
Points
263
Location
26187

jetmechmarty

Project collector
Top Contributor
XS650.com Supporter
Messages
5,931
Reaction score
16,871
Points
688
Location
Coldwater, Mississippi
As far as synching the carbs,
It's done with the engine running, right before you begin enjoying the fruits of your labor. You will do a BENCH SYNC as the last step before you install the carburetors on the engine.

Spend my money? What money?
This is going to cost money, but you're going to own tools. It might be almost as cheap to just buy this:
1662057981812.png

HOWEVER, not as rewarding.
 

jpdevol

XS650 Guru
Top Contributor
XS650.com Supporter
Messages
1,363
Reaction score
2,869
Points
263
Location
26187

Attachments

  • img060.pdf
    1.1 MB · Views: 13
Top