Low CC Sport Bike Review | Page 3 | GTAMotorcycle.com

Low CC Sport Bike Review

mistersouthpaw

Well-known member
I briefly rode @mistersouthpaw 's R3 the other day and was quite impressed with it. The engine is decently peppy even with my 230lbs on it, the handling is superb and the bike looks awesome.

I love small flickable bikes. Makes me want to go on a diet and get one for myself.
I can't wait for spring to come when I can dyno it with the new parts I got for it:

Full exhaust (TBD, selling akra gp slip on taking suggestions termignoni, toce, akra)
DNA filter
TST velocity stacks when they are done developing
R6 throttle tube (WOT stock @ 90° 70° with r6)
PC5 fuel and ignition ( shout out to Ace moto tech for the killer price!)
Vortex 7 degree clip ons
Smog block off
S20 evo tires
Powder coating the rims white (more feminine for my girl not really a performance mod)

She weighs 120lbs so significant weight reduction vs matt rain 😜😜

Bike currently:


will share when done
 

Brian P

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That's a good list. Couple suggestions. Don't install the "o2 optimizer" that comes with the PC5, it doesn't work. Leave the stock o2 sensor in place. Good exhausts will have the bung to install it. Use a long quiet mufflerr. Do that, and I know how much power it will make, you'll like it.
 

mistersouthpaw

Well-known member
That's a good list. Couple suggestions. Don't install the "o2 optimizer" that comes with the PC5, it doesn't work. Leave the stock o2 sensor in place. Good exhausts will have the bung to install it. Use a long quiet mufflerr. Do that, and I know how much power it will make, you'll like it.
Good to know, I have concerns with the exhaust being obnoxious. At this moment I'm leaning toward the termignoni with the force carbon muffler but that's subject to change at a moment's notice. What does the o2 optimizer do? I will being deleting the air injection system with the smog block offs

Any experience with dna? I am torn with a hi Flo filter because I like this bike, how well do they filter? At this point I'm still going to run it bike was pretty cheap and I have decided a rebuild is an opportunity to see what kind of compression it can make
 
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Brian P

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Hindle. Comes with oxygen sensor bung and an adapter for the stock sensor. Pick a long street muffler of your choice.

The PC5 comes with a plug to supposedly take the place of the oxygen sensor. It doesn't work. The ECU thinks it's getting a signal and sends it way rich at part load then when you lean out the map to compensate it goes too lean on cold start. Skip it. Just leave the oxygen sensor there and let it do its job.

No idea on filtering efficiency. The DNA seems ok.

Don't take apart what isn't broken. Don't rebuild a perfectly good engine.
 

mistersouthpaw

Well-known member
Hindle. Comes with oxygen sensor bung and an adapter for the stock sensor. Pick a long street muffler of your choice.

The PC5 comes with a plug to supposedly take the place of the oxygen sensor. It doesn't work. The ECU thinks it's getting a signal and sends it way rich at part load then when you lean out the map to compensate it goes too lean on cold start. Skip it. Just leave the oxygen sensor there and let it do its job.

No idea on filtering efficiency. The DNA seems ok.

Don't take apart what isn't broken. Don't rebuild a perfectly good engine.
I meant if the engine ends up dirty from the hi flo filter, it's supposed to flow 46% more than the yammie paper with 98-99% filtration, well see about that... Regarding the pc5 I will leave the stock o2 sensor in place and should I just leave the o2 optimizer disconnected and tuck it away?
 

Brian P

Well-known member
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It's supposed to plug into the harness where the (unplugged and no longer existing) stock O2 sensor originally plugged in. Leave the stock O2 sensor installed and plugged in, and chuck the O2 optimizer in the trash.
 

bigpoppa

Well-known member
Anyone know which year the 390 ktms become explosion proof?
Or at least more reliable?
 

Brian P

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The newer ones are supposedly better, I wouldn't touch the first year models. But ... The moment the roadracing classes that started out as the KTM Junior Cup morphed into WorldSBK300 or 300 Production or Lightweight Production or whatever your local organisation chooses to call it (opening the class up to other brands), the KTMs almost vanished.

I like how the RC390 looks. Always did. And they're competent on the racetrack, and on winding roads. But now, having ridden one ... I'm not interested any more. Feels coarse and crude compared to the Yamaha and Honda. (I haven't ridden a Ninja 400) The video in the original post pretty much agrees. I suppose the RC has more "character" ...
 

J_F

gringo diablo
Site Supporter
Anyone know which year the 390 ktms become explosion proof?
Or at least more reliable?
from what I've read the newer ones are even worse
still have the overheating problem

and now are plagued with electronic issues
the ones with the insect like split headlight
and TFT instrument cluster, I think 17 and beyond
 

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