Can I please ask for some observations on the lean angle clearance on the silencers on my 1960 Dominator 99.
I've recently fitted an RGM folding kickstart, the one with a little more offset that Roger sells, and it cleared the silencer when depressed, but, at the bottom of the kickstart stroke, the long arm from the clamp on the gearbox kickstart shaft fouled on the exhaust, causing it to stick in the downwards position.
To allow for this, I loosened the exhaust lock rings, and lengthened the brackets for the silencers, which attach to the pillion footrests, enough so that the exhaust pipe depressed enough to free the kickstart arm.
This obviously lowered the silencers to the extent shown in the picture I've attached.
Given that the silencers for this year are the "universal" type, which are a parallel tube, rather than the "Peardrop/Cigar" type, I put a spirit level on the top surface, and they're pretty much level.
All's working well, but I'm just concerned about the ground clearance when cornering. I took the photo, then inclined it until the silencer "grounded" when gauged buy the contact patch on the tyre, as shown by the line on the photo.
The angle measured 38 degrees from the vertical. Would this be enough for real world riding?
I have no aspirations to "get my knee down", in fact, if my knee touches the ground, something's gone seriously wrong, but I'd like the reassurance of having enough clearance not to have to think about grounding the silencers. I've looked at many photo's of other Dommies, and there's a lot of variation.
My other option is to have a small bend of around 6 degrees upwards put into the last four inches or so of the exhaust pipe, which gives an inch lift at the silencer mounting bracket, obviously more at the tail end, but I'm just trying to avoid the faff and the potential to crack the chrome when bending, if I don't need to.
I'd appreciate thoughts, if you don't mind
Andrew
Silencer clearance 1960 dominator
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A couple of things to consider...
A couple of things to consider with your lean angle experiment.
The weight of the rider (& pillion ?) will compress the rear suspension.
Cornering forces will compress the rear suspension.
Both these will contribute significantly to the silencer getting closer to scraping the tarmac.
Regards,
Duncan.
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Brackets
I think your silencer brackets are back to front.
On my 650 they came out over the silencers. This would move the silencers inwards by around 1/2" or so.
As to grounding, its something always in the back of my mind, but so far it's the stand tang that has ground out first and I do enjoy 'making good progress' when riding.
Never measured the 'static' lean angle' but I'll give it a try next time I'm in the garage.
Regards, George
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George is right ,the pattern…
George is right ,the pattern brackets look installed back to front. Non orriginal (pattern ) silencers are usually made with the mounts too far back which brings the front of the silencer too close to the frame , and a dent in the silencer fixes this !. Big Hammer!. The Orriginal pipe was angled slightly up at rear , pattern pipes tend to run horizontally but could also have a slight kick up under the box which raises the silencers at the rear. Study some early period road tests for the line . My old RGM siamese pipes kick up a bit and solved the issue
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On my 1960 Dominator the…
On my 1960 Dominator the exhaustbracket is bolted directly to the exhaust. On your picture there seems to be an extra welded-on kind of bracket.
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Thanks for the thoughts and observations
Hi all,
Thanks for all the thoughts and observations on my exhaust/silencers.
I appreciate that the suspension will compress under load, shortening the ground clearance, that's principally my concern.
There isn't an additional bracket fitted, the exhaust bracket bolts directly onto the two tapped holes in the silencer, though I agree it looks like a bracket, possibly because the silencers are round in section, rather than the oval of the usual "Cigar" silencers.
The latest Dominator service notes show them as the correct shape for the 1960 model
But I think Robert and George have hit the nail on the head.
Looking at the pictures of similar models in all the book resources I have, It does appear that there should be a "kick-up" under the gearbox, after the exhaust has passed under the kickstart. I want to lift the silencer on the supporting bracket by about 1", which equates to about a 6 degree upwards bend on the pipe.
I think mine are "aftermarket" silencers, and Robert's comment about the mounts being too far back make perfect sense.
If they were further forwards, then the bulge at the front of the silencer would clear the frame and allow me to position them inwards. As it is, I've only about 3/16" clearance between the silencer body and the frame tube on the drive side.
The offset on the brackets is about 3/8", so if I reverse them, I'm moving inwards about 3/4", and it'll foul the frame on the drive side.
I think I'm going to get our local exhaust specialist (Raysons, https://www.raysonsuk.com, have a look at the website, they're highly recommended) to put me the bends in the pipes, and then use straight brackets to take the whole arrangement upwards by 1" to 1 1/4", and inwards by about 1/2". That should help with clearance (I hope!)
Thanks again for all the advice, it's really helpful to learn from the vast knowledge within the NOC membership.
Andrew
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I put dents in the back of…
I put dents in the back of the pattern silencers as noted. they are not visible and allow the silencers to sit closer . You may be able to get the pipes bent up slightly from the front curve (a gradual bend. ) You may have to slot or drill and weld the silencer brackets to raise the silencers . the pattern brackets you have are much lighter (flimsier?) than the orriginals which are about 1/8" thick. Side stand usually grounds first . You could make new brackets that allow the silencers to sit further back if pipe is long enough . My memory from 1960 is that the wheel Axle only just clears the silencer when slid out. Very few bikes now have the orriginal nice fully curved front pipes, (one size with bends and straight sections now fits all ), there were different pipes for 88 and 99 due to height change of the barrel.
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Tucked up safe and sound
My silencers come up almost to the pillion footrests. Your brackets look rather long. My Dominator silencer brackets are the factory originals so should be correct.
You really should have enough clearance to corner in a brisk fashion should the mood take you. I doubt that's the case with yours at the moment.
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In Roadholder 458 page 15…
In Roadholder 458 page 15 you will see my red DL with the correct line of silencer . The siamese pipes do no have the best line but do kick up the silencer . Images can be viewed on line on this site.
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Thanks for the responses
Thanks very much for all the helpful information, It's helping to put my thoughts on the matter in order.
The brackets I have should be stiff enough, they are 1/8" thick stainless from Armours, they probably look flimsy because of the length, but I'm now going to use straight brackets, so some 25mm x 3mm stainless strip is on the way and, with the bend I'm going to have put into the pipes, they should be a lot shorter.
I've also ordered some 50mm x 3mm strip, in case I need to make a bracket with offset holes to move the silencer backwards.
I'll take a look at the example in Roadholder, thanks Robert.
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Hi Gordon, is that your much…
Hi Gordon, is that your much modified 650 deluxe ?, now an Atlas. If so the pipes and silencers are diferent to the 60 99 !!.
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Silencer differences
Hi Andrew,
The cigar shaped silencers were also fitted to the lightweight range.
The oval section silencers too.
The header pipe never changed.
To keep things looking straight the different silencer details become obvious.
The earlier oval section silencers have tapped mounting holes at a slope to each other. On the lightweight this means a cranked mounting bracket can be used without being handed, and securing to pillion footrest mount.
The later cigar section silencers have tapped mounting holes above each other. To pick up on the same exhaust pipe and and pillion mounts, different cranked brackets are required. These are handed, and have different crank depth to oval silencer brackets.
This often confounds owners who go through hoops trying to fit the silencers without the correct bracket, or even reversing the crank and throwing the silencers outwards.
The different mounts of cigar/oval have not been mentioned above, but are key to good silencer alignment.
Peter
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Silencer Fitting
Hi Peter,
The pattern silencers on my bike have, as you noted, the mounting tapped holes above each other, as the Armours example on the attached photo. The silencer type is correct, according to the N.O.C Dominator Service Notes page 115, showing the "1960 Model 88/99 new Cigar silencer".
The attached photo of the bike seems to show that the run immediately under the kickstart is OK, as it gives the clearance needed, but then it runs parallel to the rear of the bike, thereby lowering the silencer.
I calculated that an upwards kink in the exhaust pipe immediately after it's run under kickstart of about 6 to 7 degrees, will lift the silencer about 1" at the point where the mounting bracket attaches (more at the end of the silencer).
I think the main problem I have is the one that Robert identified a few posts ago, notably that the attachment points on the silencer are too far back, pushing the body of the silencer forwards to get under the footrest bracket, and causing the body of the silencer to foul the frame.
That stops me reversing the silencer mounting bracket to get more clearance. There's nothing wrong with the RGM kickstart, it's beautifully made, and I have a more angular AMC kickstart which also fouls the frame. The original was a "Rigid" kickstart which was OK (but only just!).
I've no problem making stainless brackets to suit wherever the silencer ends up, it's just getting the clearances and the run right in the first place.
Out of interest, could anyone kindly give me a measurement of the distance from the ground to the underside of the silencer at which they're happy to corner "briskly". It'll give me something to aim for.
Thanks again for all the advice and observations.
Andrew
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OOF !!, thats one very posh…
OOF !!, thats one very posh 99. I can see why you are focused on getting it right. Coens Dommy has some pipes with the proper curve from the engine, probably orriginals. Andrew,your footrests appear very low (which may be needed if you are tall) and will inhibit cornering and ease of changing gear as it effectively shortens the gear lever and makes it harder if you have big feet !. I put up with high rests and fit 3" raised bars to help the erganomics .Silencers appear about 3" low at wheel axle line.
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It is no longer a 99
I managed to trace the original 88 engine that was delivered in 1960. I don't know whether the popes are original but I presume they are.
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The ends of your silencers do appear to be splayed out. The cigar type silencers fit closer to the frame which would give better ground clearance. The fixings look odd compared to the cigar type?