[GUNR]

I suppose it sounds like a strange question, but I've been trying to figure out if 50km/hr in 3rd @ 2,500 rpm is labouring the engine. The alternative is 2nd @ about 3,200 rpm and that doesn't feel right to me or the engine.

3,000 - 4,000 feels like the sweet spot especially when I can sit on 80, 100, 110 km/hr in a gear in this rev range and all feels well.

This arvo, (afternoon for non-Aussies) I was almost taken out by a young woman who drove her BMW through a give way sign while looking directly into my new LED headlight and then she briefly stopped like a stunned mullet about 3m in front of me as if her car was about to fire a broadside.
I'd been sitting on 3,000 revs in 3rd which sat me nicely at 60km/hr and my sudden downshifting and the subsequent cacophany and backfiring from the megaphone must have jolted her into moving her car forward and out of my way.

What is a good gear and revs for 50km/hr (it's a prick of a speed as I don't feel that it lines up with my engine's 'happy zone'.

[gizzo]

That sounds about right to me. I'm in 2nd or 3rd at 50, depending if I can be bothered to change gear. 3, 3.5 is a sweet spot on mine and it'll sit on 4.5, 4,8 all day. 2500 rpm is about as low as I'd go when I'm underway.

[GUNR]

Thanks for verifying that. 2nd gear at 50kph sounds frenetic; I much rather prefer the feeling at 60kph in 3rd.

[KD5ITM]

A lot of the GT 535’s came from the factory with pre-detonation issues below 3,000 RPMs.  Tom of ACE Motors who is well known for building the ACE Fireball iron barrel 500.  He also has designed and manufactures his own ACE Performance branded billet aluminum performance heads and performance cam. Several years ago when he bought his first GT 535 to use as his test mule, he noted that the 535 UCE engines were prone to pre-detonation below 3,000 RPMs and during this time, was recommending that the GT 535 should not be ridden below 3,000 where the engine experiences most of its pre-detonation issues.

Do a search on this forum for “Squash Modification”.  This is what Tom and a few others came up with as the proper engine barrel modification to not only eliminate engine pre-detonation but also raise the engine compression.  Its a fairly simple and low cost modification that will increase performance.

I’v owned my ‘14 GT 535 since brand new from the dealer.  Iv got 13,500 + miles on it now.  100% of my ridding has been between 3,000 - 4,000 RPMs.  I can hit the freeway at 65mph and still be under 4,000 RPMs.

In my opinion, your lugging the engine when ridding around below 3,000 RPM.  Especially if you live in a hilly area.  Lugging an engine under a load is not good for the engine, unless the engine is designed to operate at low RPMs while under a load.  The 535 UCE engine is not designed for low RPM lugging around. 

Every type of ridding I do, in my subdivision with a 20mph speed limit, rolling quite 2 lane back roads, freeway ridding at 65mph can all be very easily achieved with ridding between 3,000 - 4,000 RPMs.  With my experience, ridding above 4,000 RPM’s, the engine vibrations are much more pronounced and get worse and worse the higher you go above 4,000 RPM’s.  Between 3,000 - 4,000 RPM’s, my GT 535 is fairly smooth. 

At 31 mph (50 kph) Im in 2nd gear with the RPM’s around 3,500 +- 100 RPMs. On the freeway at 65 mph (104 kph) Im in 5th with the RPMs right around 3,800.  The bike is quite happy. Im not lugging the engine and Im not forcing a galloping horse to run faster.

[gizzo]

Thanks for verifying that. 2nd gear at 50kph sounds frenetic; I much rather prefer the feeling at 60kph in 3rd.

No worries. I just went for a spin to run errands and paid attention to what's going on. 50 in 2nd is about 3.6k and in 3rd is 2.8ish. Both are fine. But like you say, 2nd is a bit frantic.

at 60 it's doing around 3k in second and 2.5, 2.6k in third. Again, both are fine. This engine will plop along happily from 2.5k onward. Below that it chugs a bit and there's no need for it.

Also I think maybe I'll be following your inlet procedure soonish. I noticed a bit more popping than usual at higher rpms and small throttle openings. Might be leaking a bit and time to freshen up the o rings again.

Cheers

[GUNR]

Also I think maybe I'll be following your inlet procedure soonish. I noticed a bit more popping than usual at higher rpms and small throttle openings. Might be leaking a bit and time to freshen up the o rings again.

Cheers

I've still got the popping but she definitely feels like she's hunting and snatching at 50kph @ 3.2k rpm or thereabouts. I don't mind changing down to 2nd to spin up the hills in the 50kph area, but 3rd @ around 2.6k rpm she feels comfy.

[StreetKleaver]

I re-set my crank balance factor to 63%.

The vibration zone is soft around 2500. Where as before at 58% (stock for all UCE engines) was 4500.

With the H cams the sweet spot is 3800 at 100km. 4000rpm is 110km. Below 3500 its a little laggy, why gearing it down a tooth is a good thing.

Will hum along all day at 120km and even 130km. At 4200 and 4400. After 4200 though it starts to drink the fuel, but that's how I've set the tune. Sending more fuel in that area of the map to ad a little more cooling.

The oil pump in the UCE 500 sends nearly 9 litres a minute. So if the engine is spinning, not under luggy load, she's getting plenty of oil sent around.

I've notice mainly on stock Euro 3 GT535 and classic 500s of friends have them also thats I've had a ride. There's a weird thing the stock Kihein map does. When selected in gear, free rev the motor. As the rpm settle down to idle. At 1500rpm the must fire a shot of fuel causing a "blip" as the rpms are coming to settle. Few emails back and forth to like power commander and Kihein. Even spoke to my dyno tune say that's a built in function to combat lean popping.

[GUNR]

I've just sorted the air leaks in the inlet tract so now I can have a shot at making some beneficial changes to the EJK tuner. As the popping occurs at little or closed throttle, would it be fair to assume that I should add more fuel in that area?

What sort of octane are you guys using? My son started this bike on 95 octane and I'm wondering if unleaded 91 without ethanol would be acceptable.

[gizzo]

The worse the fuel, the more this bike likes it.

[GUNR]

91 it is then..

[Taurim]

The worse the fuel, the more this bike likes it.

Not mine 
with compression measured at almost 14 bars / 200 PSI 

[gizzo]

Not mine 
with compression measured at almost 14 bars / 200 PSI 

Haha you're special 

[GUNR]

Hey Taurim, how did you do your compression test; did you dismantle the decompressor gear and put it back together again after the tes?

[Taurim]

The performance cams from HMC do not have a decompressor 

Stock cams :


HMC cams :



Hence it is not possible to kickstart my bike. Even with my full weight on the lever the crank almost does not turn.
I think it would be very difficult to jump start it too !

[GUNR]

That's interesting as I haven't seen the OEM and HMC cams together before. The HMC lobes appear to be wider at the base; does this mean longer opening duration?

How many cranks of the starter motor does it take for her to fire up (and do you free up the clutch plates before you hit the button?