Rejetting for reeds and head temp

[Scuffed98]

Planning on doing a top end rebuild on my 74 RD350. The bike has 30mm mikuni carbs and DG pipes. It still has the stock reeds so I'm planning on swapping those out for some TDR reeds. Do I need to rejet for the new reeds? I also put some cylinder head temp sensors on the bike. So I was wondering at what temps should I pull over and stop the bike. Past experience's tells me 400-425 degrees is the max temp before I have to start worrying about soft seizing. Hottest temp I got the RD350 to so far is about 350 degrees.

[quocle603]

~420 has been the temp that I have always followed. Always try to do a plug chop read to make sure you dont put a hole in the piston as well. What senors are you currently running? Ive used the trail techs in the past.

You shouldn't need to rejet for the reeds. Hows the bike running at its current settings?

Write it down, Google doc or something and go for a long ride and then make the swap to see if there was a change. Doing this has saved me wonders of "what did I do I have in there?" And document the throttle position pull.

[m in sc]

if you're running stock cages I agree, the jetting shouldn't really change.

[Scuffed98]

~420 has been the temp that I have always followed. Always try to do a plug chop read to make sure you dont put a hole in the piston as well. What senors are you currently running? Ive used the trail techs in the past.

You shouldn't need to rejet for the reeds. Hows the bike running at its current settings?

Write it down, Google doc or something and go for a long ride and then make the swap to see if there was a change. Doing this has saved me wonders of "what did I do I have in there?" And document the throttle position pull.

I'm using a couple of trail techs. Figured I wouldn't need to change my jetting. In the past whenever I changed reeds it was always with modifications where I had to change jetting. The bike runs well so far. Its a little bit rich on the bottom end and pulls well until I hit about 80mph. On high speed runs I've been noticing that the bike starts to misfire and knock at around 7000rpm. I have the timing set up at 2.00mm BTDC so I'll try to bump it down to 1.8mm BTDC today and see if that fixes my issues.

[quocle603]

The 1.8mm btdc will help with today's gas grade. Tons of mods to do on these bikes to "help" with performance but you sometimes take a loss. I would try to fit it best to your style of riding and preference.

[m in sc]

make sure the float seat orifice is big enough and you're not starving the carbs.

[1976RD400C]

My modified 400 seems to run about 280 degrees and up to 330 when opening it up.

[Scuffed98]

I bumped the timing down to 1.8 yesterday and the bike runs a little cooler. I did end up finding out that my spark issues are from my condensers being bad, So I ended swapping those out for some extra condensers I had for my car.
On a side note would a bike with stock porting but bolt on modifications benefit from installing RZ350 intakes with the crossover tubes?

[quocle603]

It might help with your mid range transition with those chambers, but i hear the DGs did not do much without modification. Do you currently have an issue with that right now??

[Scuffed98]

It might help with your mid range transition with those chambers, but i hear the DGs did not do much without modification. Do you currently have an issue with that right now??

No not really. I'm quite happy with my mid range right now. The powerband on the DG pipes doesn't feel peaky on the high end enough to justify a crossover intake. Assuming all the crossover intakes do is help with the low/mid range.
I would like to swap out my DG's for something else one day but I can't seem to find anything else.

[m in sc]

Lomas makes pipes. specii but?

[RDnuTZ]

It might help with your mid range transition with those chambers, but i hear the DGs did not do much without modification. Do you currently have an issue with that right now??

what does the modification involve?

[Scuffed98]

I heard that JL stopped shipping pipes into the US. I would really like to try a pair of Spec ii pipes. Since I heard they work really well with stock porting. However, I don't know who to get in touch with to try to buy a pair. I remember seeing a website a few months ago but now it's gone.

[m in sc]

i hope not. i have a set waiting to come in.

[quocle603]

I heard that JL stopped shipping pipes into the US. I would really like to try a pair of Spec ii pipes. Since I heard they work really well with stock porting. However, I don't know who to get in touch with to try to buy a pair. I remember seeing a website a few months ago but now it's gone.

I would probably just keep the stock intakes instead of the banshee ones with crossover. Do what you will but your bike is pretty much stock with dg and 30mm carbs. How are the 30mm carbs? I assume they are VM


What are you looking to achieve? If you want high rpm hitting pipes, then try to find lomas and spec II. I have an extra set of spec II that I was able to pick up for under 300 bucks locally.