1971 TR6C Exhaust Fitment

[OZSimon]

Hello Guys. Has anyone fitted new exhaust pipes to a 1971/1972 OIF TR6C in the past or recently. I cannot find new exhaust pipes with the correct part numbers for the oil in frame TR6C 650's (from Triumph parts manuals) for 1971 lower pipe 71-1900 and upper pipe 71-1901 or 1972 lower pipe 71-2334 and upper pipe 71-2632. I can only find these front pipes for TR6C's up to 1971 (non OIF) with part numbers listed as 71-0022 and 71-0024. Some on line suppliers I have contacted say these earlier pipes will still fit my bike... but other suppliers say they won't. I don't want to risk buying pipes online, importing them to Australia and then finding they won't fit my bike. Does any member know if these pipes are compatible. Has anyone fitted them successfully in the past or does anyone know if there is a physical difference in the shape of OIF and non OIF front pipes. I have the correct H piece connector sleeve and both upper and lower silencers/mufflers and rear mounting bracket for my 1971 OIF TR6C. I am looking forward to any replies and/or advice. OZSimon.

 

[speedrattle]

for 1971, triumph switched from dry frame to OIF, as you know. the earlier bikes had a spigot screwed into the exhaust poets, and the pipe was fitted over them and clamped with the rosettes. the OIF cylinderheads use pipe-in-head exhausts that slipped into holes without a clamp of any kind, being held by the crossover tube or the brackets at the crankcase bolt.

OIF pipes will not easily fit dry frame cylinder heads. dry frame pipes will easily fit OIF heads if you install aluminum or steel press-in exhaust spigots and rosette clamps.

so far as i know, the mounting tabs on the exhaust pipes and the position of the rear of the pipe where the silencer attaches are the same for dry and OIF machines. i routinely mount dry frame pipes-aftermarket styles or stock pipe styles- to my 1972 T120 with no modifications other than the added spigots.

i dont know about how the high/low TR6 pipes mount at the back, but i am pretty sure that any minor height or length difference could be accomodated by fitting a bracket made to fit

 

[OZSimon]

for 1971, triumph switched from dry frame to OIF, as you know. the earlier bikes had a spigot screwed into the exhaust poets, and the pipe was fitted over them and clamped with the rosettes. the OIF cylinderheads use pipe-in-head exhausts that slipped into holes without a clamp of any kind, being held by the crossover tube or the brackets at the crankcase bolt.

OIF pipes will not easily fit dry frame cylinder heads. dry frame pipes will easily fit OIF heads if you install aluminum or steel press-in exhaust spigots and rosette clamps.

so far as i know, the mounting tabs on the exhaust pipes and the position of the rear of the pipe where the silencer attaches are the same for dry and OIF machines. i routinely mount dry frame pipes-aftermarket styles or stock pipe styles- to my 1972 T120 with no modifications other than the added spigots.

i dont know about how the high/low TR6 pipes mount at the back, but i am pretty sure that any minor height or length difference could be accomodated by fitting a bracket made to fit

Hi speedrattle. The cylinder head on my 1971 OIF TR6C comes with the threaded exhaust ports and I have the 41mm screw in adaptors fitted (part no 70-9516)

for 1971, triumph switched from dry frame to OIF, as you know. the earlier bikes had a spigot screwed into the exhaust poets, and the pipe was fitted over them and clamped with the rosettes. the OIF cylinderheads use pipe-in-head exhausts that slipped into holes without a clamp of any kind, being held by the crossover tube or the brackets at the crankcase bolt.

OIF pipes will not easily fit dry frame cylinder heads. dry frame pipes will easily fit OIF heads if you install aluminum or steel press-in exhaust spigots and rosette clamps.

so far as i know, the mounting tabs on the exhaust pipes and the position of the rear of the pipe where the silencer attaches are the same for dry and OIF machines. i routinely mount dry frame pipes-aftermarket styles or stock pipe styles- to my 1972 T120 with no modifications other than the added spigots.

i dont know about how the high/low TR6 pipes mount at the back, but i am pretty sure that any minor height or length difference could be accomodated by fitting a bracket made to fit

 

[OZSimon]

Greetings speedrattle. The cylinder head on my TR6C is a 1972 version as I prefer the later rocker boxes with the long inspection/timing covers. It comes with threaded exhaust ports to take the 41mm exhaust pipe adaptor/spigots (part no 70-9516) which I have fitted along with temporary plastic plugs to keep unwanted bits out during long periods of inaction. See attachments. I know that aftermarket pre OIF TR6C pipes will fit over the spigots with the rosette clamps at the front... but I have conflicting advice from suppliers that they will attach to the rear H piece without re bending or alteration. I cant find any information on are pre OIF and OIF TR6C exhaust pipes the same shape with the same bends etc. The part numbers are all different for pre 1971, 1971 and 1972 but this could be just yearly dating changes or there might be a change in shape involved. I am hoping to contact a member who has fitted the pre OIF pipes to a OIF TR6C. I cannot find OIF TR6C exhaust pipes for sale online anywhere. Many thanks. OZSimon.

 

[speedrattle]

thats super interesting. sometime in 71 or v early in 72 they went to the later heads and rocker boxes. my 72 is a T120RV DG, and came with thr later configuration.

41mm works out to be 1.75-inch pipes, assuming 0.080 wall thickness? do i have that right?

which head steadies came with your 71? the 4 dog bones or the single strap?

i dont know anything about the high TR6 pipes. if nobody volunteers an answer you may be stuck experimenting.

 

[OZSimon]

thats super interesting. sometime in 71 or v early in 72 they went to the later heads and rocker boxes. my 72 is a T120RV DG, and came with thr later configuration.

41mm works out to be 1.75-inch pipes, assuming 0.080 wall thickness? do i have that right?

which head steadies came with your 71? the 4 dog bones or the single strap?

i dont know anything about the high TR6 pipes. if nobody volunteers an answer you may be stuck experimenting.

My head steady is the single strap type. I have both (a later 72 ?) T120 and a (later 72 ?) TR6 cylinder head at home to work with and both are fitted with the small dowel pin holes to accept the later rocker boxes with the long single tappet adjustment cover plate which I prefer. The spigots are stated as 41mm 1 5/8'' I have not measured the wall thickness. I know these spigots will accept the pre OIF aftermarket pipes I can find but I am more concerned about the fitment at the rear with my H piece and silencers. That's why I am hoping I can find a member who has done this fitting... or like you said experiment with them.

 

[speedrattle]

1-5/8 inches is not a standard size, unlike 1-1/2 and 1-3/4. i use 1-5/8 in my LSR race bike, but i have to weld up the pipes myself.

i just measured a factory stub in a 1969 head at OD 41.7mm.

the OD of the pipe on my LSR is 1.769 to fit over the customized (not by me) welded-in stubs, then stepping down to an OD of 1.631 for the length of the pipe.

you can fit any rocker boxes you want to the dry or OIF cylinder heads, so long as you figure out the head steady. the later dowels in the OIF heads do not interfere with the more compact (and better reinforced) earlier rocker boxes. the later boxes require the dowels because they lack the metal deleted in order to accomodate the two-piece head bolts.

i use late 72 OIF 9-1/2-bolt heads in my LSR with early rocker boxes to fit into an early frame.
i realize that you know this stuff but other people reading this in the future might be interested in the interchange information

 

[OZSimon]

1-5/8 inches is not a standard size, unlike 1-1/2 and 1-3/4. i use 1-5/8 in my LSR race bike, but i have to weld up the pipes myself.

i just measured a factory stub in a 1969 head at OD 41.7mm.

the OD of the pipe on my LSR is 1.769 to fit over the customized (not by me) welded-in stubs, then stepping down to an OD of 1.631 for the length of the pipe.

you can fit any rocker boxes you want to the dry or OIF cylinder heads, so long as you figure out the head steady. the later dowels in the OIF heads do not interfere with the more compact (and better reinforced) earlier rocker boxes. the later boxes require the dowels because they lack the metal deleted in order to accomodate the two-piece head bolts.

i use late 72 OIF 9-1/2-bolt heads in my LSR with early rocker boxes to fit into an early frame.
i realize that you know this stuff but other people reading this in the future might be interested in the interchange information

I am basically rebuilding this bike from a worse than basket case state. I had to buy and import a compatible 1971 OIF T120R frame as the one I was given had been badly chopped and there were no TRC stamped frames available. My motor crankcases are 1971 TR6C . I like the TR6C high pipes. I owned original Bonnies and Trophys in the early 70's but these were all pre OIF. I also had a lovely 750 bonnie a bit later on. This bike is a long term retirement rebuild to keep busy and it won't be 100% stock standard when I finish it. I am going to experiment with the 2 carby T120 cylinder head which is on the bike at the moment as the TR6C Trophy head needs a lot of work to restore it. I have both single and dual carb refurbished standard OIF air boxes and covers ready. I will run both on completion of the rebuild to see which I prefer. I have seen the TR6C pipes on a few twin carb 750 Bonnies here in Australia and I like the look. I want to rebuild this bike with the features I like as it is a retirement exorcise and it won't be a concourse example with matching numbers etc. I enjoy looking for parts on the net and talking to other riders like you. My problem with these TR6C exhaust pipes is the cost of buying, importing to Australia and paying our GST and import taxes and then having trouble fitting them. But that is only part of the joy of rebuilding older British bikes. I also have a 1970 Royal Enfield series 2 Interceptor which I am rebuilding from all new old stock parts. My motor is all NOS and basically brand new. The only used parts on the bike is the frame and front wheel hub. Again it is a retirement project I started about 6 years ago. My Triumph I started about 2 years ago.

 

[speedrattle]

the advantage of what you are doing is that you can mix and match to get what you like. put up some pictures when you get a chance. lots of people will offer what they know to help you solve the problems that come up.

 

[OZSimon]

the advantage of what you are doing is that you can mix and match to get what you like. put up some pictures when you get a chance. lots of people will offer what they know to help you solve the problems that come up.

I totally agree. It is good to mix and match. I want the end product to be what I want not supposedly concourse for the experts to minutely check over and tell me I have the wrong type of head on a certain bolt. My Interceptor will be close to original with the exception of an earlier frame and electronic ignition and belt drive. My Triumph is my personal interpretation of how I want it. I remember in the 1970's buying new and second hand Triumphs and a new Norton 850 Commando and we always made changes and improvements with electronic ignition and better sealant gaskets to stop them leaking oil from new. Plus the wonderful Lucas electrics ! I have attached some pics of my Triumph and Interceptor builds. My Triumph is on my kitchen table and my Interceptor motor is in pride of place in the loungeroom. Where else would you put them !