To port... or not to port. That is the question.

[soonerbillz]

  Working up the parts for my R5. This is going to be a resto streeter that will ridden often.
It has YDS7 case/crank and will be fitted with a RD350 tranny and clutch. I'm putting R5 jugs on it..  with stock R5 carbs.
I'm not looking at chambers.. I want to keep the stock exhaust.
Will I really see any worthy benefit out of having the thing ported? I won't be racing the bike... but I do want good reliable performance.
I tried looking at multiple sites on the subject but it's like impossible to come on to real solid answers.
The bike will not be modded beyond what I said above. Stock brakes... ect.
Reason for the question is I saw the porting post offering the service and if it is worthy or not.. better to know now before I build up the motor.
Thanks

[rodneya]

If you are not doing other mods or changing pipes, I would just leave it stock.
Porting and other mods turn them into even bigger gas guzzlers than they already are. Not so convenient on a bike that gets ridden a lot.

[teazer]

Some of us are big fans of ported motors.  No need to go mad though.  A light clean up and port matching won't hurt and a "stage 1" port job should wake it up a bit. 

[rodneya]

Dont get me wrong, I love modified motors. My 73 RD should be making mid 80's Hp if I were to get it dynoed, but I have changed everything from the intake through to the exhaust and ignition. Super fun to ride, but an absolute pig on gas.

My 74 Rd is completely stock except for a y pipe on the intake. I thought about getting some porting done when I put the motor together, but decided that with stock pipes any small gains achieved would not really be worth the money spent. Still rips pretty good in stock form.

[teazer]

Agreed, but more is always more.  I think I once had a stock RD400 but with stock pipes it was still ported and that perked it up quite a bit.

Was it worth it?  Well that's an individual judgement call.  I had it professionally ported and it looked great but when I measured side to side, it was all over the place, so I had to finish the job.  So yes and no to that question.

With stock pipes it should be possible to do mild porting and raise compression and correct squish for a reasonable cost with worthwhile results.  I can't speak for the OP though. 

[racerclam]

Definatly gains can be made without going wild in port timing , Exaust port shape is importand as well as boost port angle and entry , equalizing boost and transfer port height and exit algles , Much can be done to improve even with stock pipes   give ne a call if you want to know more  richstaylordporting.com  702-858-9177

Rich

[Organicjedi]

My 400 is modified from intake to pipe with a stage 1 port. Stock but modded VM28s. I still get about upper 30s-40mi/ ga. And I'm pretty hot on the throttle.

I'm on reserve at about 100mi on a 3.2 ga tank. I've pushed it to about 118 miles on a tank of gas. Still wasn't empty.

[m in sc]

you bottleneck will be the pipes but a good cleanup will def help. Id consult some old school guys who ran in production class road racing, and had to run stock pipes. Scott Clough comes to mind.

[Yamaha 179]

I ran the first AMA Superbike Production Series on a RD 350 (along with Scott Clough and a bunch of other guys).  We had to keep the bikes appearance stock but could upgrade suspension, remove lights, etc.  We could port the engines but had to retain the standard exhaust systems.  I ran Daytona and a almost all the other AMA road races east of the Mississippi in that configuration and it was a lot of fun.  My street bikes since that time have always included at least one, sometimes two RDs, and they always had stock exhaust
systems.  Some were ported, some not.  Almost every one had the cylinder heads reconfigured to change the squish clearance because the OEM heads are terrible.  Your engine would probably benefit from having the ports MATCHED to stock specs and cleaned up a bit but there is no need to have them modified.  It would just make riding around town a pain in the butt.  If nothing else have the heads turned to decrease squish clearance.  If you put a lot of miles on the bike an improved ignition system would be a benefit but we had to run the battery and coil when we raced them and while they took a lot of attention they worked well.
Lyn Garland

[soonerbillz]

I ran the first AMA Superbike Production Series on a RD 350 (along with Scott Clough and a bunch of other guys).  We had to keep the bikes appearance stock but could upgrade suspension, remove lights, etc.  We could port the engines but had to retain the standard exhaust systems.  I ran Daytona and a almost all the other AMA road races east of the Mississippi in that configuration and it was a lot of fun.  My street bikes since that time have always included at least one, sometimes two RDs, and they always had stock exhaust
systems.  Some were ported, some not.  Almost every one had the cylinder heads reconfigured to change the squish clearance because the OEM heads are terrible.  Your engine would probably benefit from having the ports MATCHED to stock specs and cleaned up a bit but there is no need to have them modified.  It would just make riding around town a pain in the butt.  If nothing else have the heads turned to decrease squish clearance.  If you put a lot of miles on the bike an improved ignition system would be a benefit but we had to run the battery and coil when we raced them and while they took a lot of attention they worked well.
Lyn Garland

Thank you Lyn for your reply.
Very good experienced advice. I really don't want to turn a street motor into a unhappy racer. I have another project for that. I just saw all the other posts on the subject and wanted good advice.
I'll talk to some of the guys that are offering their services and try to get what's needs but not what doesn't.
Again.. thanks.