1967/1969 Bonnie Rebuild Desert Sled Project
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Some cam and bushing information. So I recently did a dry run with my cams and putting the engine cases together and found some binding in the timing side intake cam bushing. I had previously modified the exhaust side by shortening it on a whetstone. So the binding was the cam shoulder rubbing against the inside of the cam, so I should have also modified that bush.
I’ve got new LF Harris cams, 70-3134 intake and 70-9989 exhaust, and these both measure about .997-.998 from shoulder of the timing side to shoulder where the cam gear gets set up against. I’ve also a new set of sintered bronze bushings, also from LF Harris via Classic British Spares. Both timing side bushes measure .9965-.9970 overall length. So I guess I was a bit surprised as I thought that these might be manufactured in order to be used as is. However there is no way for these to work without reducing the length on both in order to avoid them binding when the cases are assembled.
Maybe this is no surprise to others?
Thanks for any comments.
I’ve got new LF Harris cams, 70-3134 intake and 70-9989 exhaust, and these both measure about .997-.998 from shoulder of the timing side to shoulder where the cam gear gets set up against. I’ve also a new set of sintered bronze bushings, also from LF Harris via Classic British Spares. Both timing side bushes measure .9965-.9970 overall length. So I guess I was a bit surprised as I thought that these might be manufactured in order to be used as is. However there is no way for these to work without reducing the length on both in order to avoid them binding when the cases are assembled.
Maybe this is no surprise to others?
Thanks for any comments.
As I’m waiting for some bearings and other engine parts before I start putting my motor back together - I’ve been taking apart my wheels and other bits. When taking apart the rear wheel today I found that the brake plate was bent. I’m wondering if anyone has experience with this sort of damage. Would it be possible for me to attempt to bend this back into shape? Thanks for comments!
You could try, but it looks pretty bad. The shaft and the sleeve it rides in need to be VERY straight or you could suffer a brake lock-up at speed. I think you can find decent replacements used on e-bay.
Yes, I'll get it all apart and see what other damage there might be.
I’m working on my fork rebuild, needing to replace most everything. I have a spring question however. I understand the Yellow/Green painted springs are the heavy duty springs, and the Yellow/Blue painted are the standard springs. It looks like the springs from my fork are ? Green/Red? - or ?Green/Yellow? - or ?Green/Orange? I’m wondering if anyone can identify these? Thanks.
Another fork question: My forks are pretty beat up. I need to replace the stanchions, dust excluder nuts, shuttle valves, restrictors, bearings, etc. Pretty much everything is corroded in some way except for the triple trees, damper, lower members and a few other bits. So looking at buying replacement/rebuild parts for these major items I find I am going to spend quite a lot to re-build these. I’m wondering if there is any alternative to this? Like some other fork types that might fit these triple trees or what? Or looking for another fork that I would have to rebuild - but of course it would have to have a lot more good parts. Thanks for any advice.
New parts aren't as expensive as different forks that are easily adaptable, in near-new condition.
Those springs are yellow-green from what I see
Those springs are yellow-green from what I see
Yes, that is what I am finding as I'm looking for options.
Taking a closer look at my forks I believe the PO of whoever built the forks last did not assembly them properly. My forks have the shuttle valve H2154, and restrictor. But the restrictor in my forks looks like the restrictor from 1967, part no H1499. From the parts catalog the H1499 looks a lot bigger than the restrictor from the 1969 parts catalog, part no H2090. The older restrictor does not even fit into the shuttle valve. Anyway, just another of the items that reveals this bike was likely put together without a lot of care.
Fork rebuild question. I am getting parts to rebuild my forks. I am pretty sure these forks are from 1969. The lower member drain plug from these forks are in the first photo. When looking for new drain plugs I see the plug for 1969 as in the second photo (screen capture). I’m just wondering if considering the drain plug type that came out of my forks, could it be they are from a different year than 1969? Thanks.
Monobloc Carburetters - Carburetter type number e.g 376 or 389, followed by size designation.
376 series, size designations are: 1516 for 15/16" bore diameter, 1616 for 1" bore diameter and 1716 for 1 1/16" bore diameter.
389 series, size designations are: 3632 for 1 1/8" bore diameter, 3732 for 1 1/16" bore diameter. Both series are only available in right hand adjuster form, 'Short' float bowl versions ('S' designation) are available.
I putted new ones and the result is fabulous, There are some on Amal Carbs 389/95 Triumph T120c 1966 T120tt 1965-66 for sale online | eBay
Serge, thank you for the information. I am still needing to get new carburettors. I am putting my engine back together again and will need some in a month or so. Thank you for your advice!
I’m getting to the point where I need to get some new shocks. As this is a scrambler type of build, I wondering if there might be some recommendations from the forum. I’ve looked at several types: Koni dial a rides, Girling type 13.4”, Hagon premium shocks. The Hagons are more than twice as much as the the others. I’d appreciate any advice on the matter. Thanks!
Ikon shocks.
Got it!
How free should the crank run when assembled? So I’ve got my cases together and am wondering how free the crank should be moving? I’ve hear that it is good if when assembled, and the rods are at their lowest point, they should be able to rise themselves due to the weight of the flywheel. Mine don’t at this point. The crank and rods feel smooth and uniform when I run the crank around, however I do need to manipulate it myself by pushing the rods around the crank. I’d appreciate any comments on this in case I need to take it apart again. Thanks!!
In addition to my concern about the crank’s freedom of movement, I noticed that every once in awhile the left rod stuck slightly at the same place. It didn’t happen all the time but when it did it was at the same place. So when I loosed the case bolts quite a bit, then the crank ran freely and was able to rotate on it’s own when the rods were at the bottom of the stroke - very nice and smooth. However I still had that small hitch/glitch/check occasionally on the left rod right at the same place. It was when the big end of the rod was about 110 degrees from the top - so the big end is towards the bottom of the case. This was quite consistent, it didn’t always happen, but when it did it was in the same place. So I could not really have a clear conscience to not check this out. So I separated the cases and when I checked the left rod there was not problem with it’s rotation on the crank. So I noticed that the end of one of the left rod bolts seemed to have some abrasion, that is some of the black was off of the nut edge. I thought that maybe it was hitting the inside of the case somewhere. I also found a shiny spot on the inside of the case that seemed to align with where/when I thought the rod was sticking. My rod bolts are new from JRC, they were the same dimension as the old rod bolts. I spoke with a gentleman at JRC about the bolts and he sent them my way. So I got out my old bolts, and it looks like the edges on the top of the bolt(s) were ground down a bit and polished. I suppose someone may have done this before assembling. So at this point I may need to get my Dremel out and take a bit of the edge of these rod bolts off. While I just have them sticking at one point I should probably grind polish each of them because I wonder if when the engine heats up and expands there could potentially be more rubbing. Has anyone had experience with this sort of thing? Thanks!
I would lightly dress both the case(s) and the rod bolts EVER SO SLIGHTLY.
Does the rod have the same stiction when the crank is OUT of the cases? If so, you need to disassemble it off the crank and look for where the interference is on the shell-to-journal contact patch. Remember not to mix the rod & cap orientation up...
I was careful with the rod and rod cap orientation so I'm sure it is as it was. It turns freely on the crank - made sure to check this before assembly. So I'm pretty sure it is this slight contact with the rod bolt head. Crazy.
