1991 TDM 850 - Vaccum hose connection advice please

newmechanic · Derestricted Danger Joined: 03 Oct 2016 Karma :

I'm rebuilding my first project, a 1991 TDM 850 and I was hoping for some advice about reconnecting vacuum hoses from the inlet manifolds.

When I took the bike apart the #2 cylinder hose was attached to the manifold but the other end was hanging loose. The bike had an MOT and ran fine before I began disassembly.

Everything else is connected up and I can't see where this rogue hose might fit

I think the fuel pump is an aftermarket one because it doesn't quite fit the mounting holes in the frame. (I've got an original replacement on the way) The carbs are original.

Grateful for any advice because this is holding up my first restart since rebuilding the bike Sad

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Riding 20+ years. Working on my first project

chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :

Don't take this for Gospel but I believe the Mk1 850 Fuel pump is known to be shit. A common mod is to replace then with a pump from an R1/R6.

The old one is operated by a Vacuum and the R1 ones don't so that could explain the redundant hose.

I've never even sat on a mk1 but own a TDM900, I also frequent the TDM forums which is where I'm sure I've heard of this mod. I think it gives you more power at the top end too. I'd start the bike and see how it runs, if well you have no problem.
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Well, you know what they say. If you want to save the world, you have to push a few old ladies down the stairs.
Skudd:- Perhaps she just thinks you are a window licker and is being nice just in case she becomes another Jill Dando.
WANTED:- Fujinon (Fuji) M42 (Screw on) lenses, let me know if you have anything.

newmechanic · Derestricted Danger Joined: 03 Oct 2016 Karma :

Thanks Chris

I did some digging after your post. I think the pump I have is from an SV650 (similar pump pictured) and seems to be vaccuum driven too. The used stock replacement I ordered arrived today and both just have three outlets so no clues there.

It's frustrating because the redundant pipe has p-clip on it, suggesting its been connected at some point. As you say, I'll give the bike a try and see what happens
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Riding 20+ years. Working on my first project

chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :

Any pictures? It could be a drain or breather of some kind.

https://www.fowlersparts.co.uk/parts/4085153/tdm850-3vd1-1991-999-a/intake

Is it part3? It looks to be blocked... Carpe TDM would give you a better answer.
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Well, you know what they say. If you want to save the world, you have to push a few old ladies down the stairs.
Skudd:- Perhaps she just thinks you are a window licker and is being nice just in case she becomes another Jill Dando.
WANTED:- Fujinon (Fuji) M42 (Screw on) lenses, let me know if you have anything.

newmechanic · Derestricted Danger Joined: 03 Oct 2016 Karma :

You know, I think you've cracked it, Chris

I think it is the part you mentioned. OCD has got the better of me and I've ordered the missing blanking pin.

Thanks so much Thumbs Up

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Riding 20+ years. Working on my first project

chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :