Opinions on twin spark vs single spark

[Tray]

Here's the deal. I'm looking for good road bike. RT is at the top of the shortlist.

My question is... Does the twin spark make that much difference over the single spark?? Is that all that changed on the 04's? Are the rear brakes still very sensitive or did they make changes?

[ClayG]

The twin spark is, in my experience, much smoother/less vibration than my '97 R1100R was. Also, the surging is a thing of the past. Can't comment on the sensitivity of the rear brake relative to earlier versions, but on my '04 1150RT, it's pretty darn sensitive.

[Tray]

The twin spark is, in my experience, much smoother/less vibration than my '97 R1100R was. Also, the surging is a thing of the past. Can't comment on the sensitivity of the rear brake relative to earlier versions, but on my '04 1150RT, it's pretty darn sensitive.

 

I see. Do you notice any power difference?

[270]

I never spent much time on older oilheads, so I can't comment on power. I will say that I haven't ridden two oilheads that "feel" the same! Having said that...

 

The latest iteration of any motor tends to be the best. BMW said the 2-spark was for emissions, but I don't think I've heard anyone complain about surging with a 2-spark.

 

The brakes will certainly be up to you as an individual. I like them. From what I hear, the '04's are not as sensitive as earlier linked/assisted RT's.

[ShovelStrokeEd]

Tray,

I have both a twin spark and a single spark bike of recent vintage. Neither is a RT. I don't notice too much of a difference in the way the bikes run. They are kind of apples and oranges in that the 1100S, the single spark bike is a bit of a hot rod and the GS Adv, the 2 spark, has a more sedate motor. My one comment would be that the GS seems to stay in tune longer. Some of that might have to do with the GS having more than double the milage that the S does despite the opposite 2 year disparity in their ages. GS-'04, S-'02.

 

I cannot comment on the brake issue as neither bike has linked brakes. The GS has wonderful partially linked, servo assisted brakes. The 1100S has no ABS or servo systems whatever and I love its brakes as well. I would not let the brake issue keep me from a good deal on an '03 or '04 RT. I understand the '03 to be a bit more sensitive than the '04. I would imagine that a little up close and personal time in the parking lot would solve most of your problems anyway.

 

Ed

[Peter H.]

I am very satisfied with the performance of my twin spark 04 RT. I can not detect any surging at any RPM level.

 

I would not call the rear brake on mine "sensitive". A resonable amount of pedal travel and decent pressure are required to effect stops.

 

Peter

[ClayG]

Hard to say re power difference. The 1150RT is rated w/ more horsepower, but the 1100R was a lighter bike. I'd say it is a wash as far as what I perceive.

[Bill J]

I had a '96 RT and now ride an '04 2-spark. My older one definitely surged and my new one definitely does not. The '04 also seems to have more power, but not enough to really matter, if you ask me.

 

The brakes work great-aside from the Borg collective servo whining. I have never noticed too much sensitivity in the rear brake, but I understand they tweaked the brakes a year or two ago.

[OldMotor]

Two months ago I went from an 02 to an 04. I had 60,000 miles on the 02 when I traded it in. The 04 now had 4,000 miles on it and runs great. The 02 that I had pinged, surged and once in a while would die at stop lights. (I pulled the cat plug on the 02 and it ran better) I think the 04 has a little better pick up, but the top end is about the same. Not great big changes, but noticeable.

[PPDGene]

Now I have to step in and defend my 03 1150RT single spark. My 03 run great with no noticable surge. So it really up to the individual bike. I have heard of some unhappy Dual spark owners as well as single spark owners. So who knows it depends on the individual bike.

[TonyS]

I have a 2000 1100R and an 04 RT (dual spark). Both are maintained by the same mechanic (DIY). The dual spark will idle along with the clutch out where I tend to coast along with the clutch in on the R to avoid the bit of surging. Up to 4K rpm the R is smoother with no surging, above that they're about the same. The R starts much better and runs better when cold. Power is hard to judge because the R is much lighter and the gears are different, call it a wash. The brakes are different; I really can't say one is better or easier to modulate than the other. I did prefer the R's unlinked, no assist system until I bled the brakes on the RT, with much help from Cory (StrongBird), and got rid of a lot of air from the rear control circuit. It's surprising we're finding such different characteristics from machines, which are supposedly built all the same. I suspect a lot of the differences people are reporting are due to the mechanic performing the service. I still feel I'm not getting the RT completely correct with the throttle balance.

[randy]

if you are mechanically inclined save your self some money. Buy a 2000 model R1100RT and do the san jose dual plug upgade. I did it myself on my bike, I know there are about a dozen other board members who have also done, some themselves, so have taken it to a dealer, and I have heard only 100% positive reviews. My bike ran fine before, but I noticed a better engine when I was finished. It idles at 800 rpm just as smooth as silk, revs very easy (i have GS tubes and cat removed with stock CO sensor still in place) and it pulls as strong as any RT I have ever ridden. Chris K helped me with the project and has ridden the bike before and after. I like the gearing of the 1100 bike a little better, and so this was my solution. But I have ridden a early 04 1150RT and felt it was every bit as good as my bike. However I do not ride the highway that much, and for me, I felt the 1100 gearing was a better match for the mountain riding I enjoy the most. I had the opportunity to buy and install a GS 5 speed gear box in my RT, and I wish I had done it. I think the lower gearing of the GS would have really worked with the 1100 RT.

[RPG]

Ray, having an '02 and now an '04 (single vs. twin spark), I can only comment on my experience.

 

The '02 was absolutely horrible the day I brought it home from the dealer. Surging? You want surging? Mine could have been the poster child.

 

I stuck with it and through the generous contributions of many members of this board, I was able to "tune out" about 90% of it. At least to the point where someone else riding it might not notice it. Always bugged me that it was always somewhwat there and I couldn't get completely rid of it. (At least through normal tuning methods)

 

However, cold starting never was acceptable. The motor would crank and crank and crank.

 

When I hit a deer last summer and totalled it, I decided to ride an '04 as everyone was saying how improved they were.

 

Test rode one and was immediately impressed on the overall improvement in response of the motor, NO SURGING!, much smoother idling and generally a much better behaved motor.

 

Ordered one last August and couldn't be happier. Other improvements over the '02:

 

Transmission now made by Getrag. Shifting much improved. First just falls into place, no grinding on upshifts or downshifts.

 

Stainless Torx screws for most of the body panel fasteners. Adds a touch of class over the black painted screws of the past.

 

Exhaust has a deeper tone to it. Not sure why but it is noticeable.

 

Better fuel economy. Latest 400+ mile trip netted nearly 50mpg, while averaging 70-80mph. The '02 never got better than about 44 in any situation.

 

Brakes are about the same sensitivity wise. That is to say excellent.

 

Hope this helps,

 

Rick

[Tray]

Ray, having an '02 and now an '04 (single vs. twin spark), I can only comment on my experience.

 

The '02 was absolutely horrible the day I brought it home from the dealer. Surging? You want surging? Mine could have been the poster child.

 

I stuck with it and through the generous contributions of many members of this board, I was able to "tune out" about 90% of it. At least to the point where someone else riding it might not notice it. Always bugged me that it was always somewhwat there and I couldn't get completely rid of it. (At least through normal tuning methods)

 

However, cold starting never was acceptable. The motor would crank and crank and crank.

 

When I hit a deer last summer and totalled it, I decided to ride an '04 as everyone was saying how improved they were.

 

Test rode one and was immediately impressed on the overall improvement in response of the motor, NO SURGING!, much smoother idling and generally a much better behaved motor.

 

Ordered one last August and couldn't be happier. Other improvements over the '02:

 

Transmission now made by Getrag. Shifting much improved. First just falls into place, no grinding on upshifts or downshifts.

 

Stainless Torx screws for most of the body panel fasteners. Adds a touch of class over the black painted screws of the past.

 

Exhaust has a deeper tone to it. Not sure why but it is noticeable.

 

Better fuel economy. Latest 400+ mile trip netted nearly 50mpg, while averaging 70-80mph. The '02 never got better than about 44 in any situation.

 

Brakes are about the same sensitivity wise. That is to say excellent.

 

Hope this helps,

 

Rick

 

Rick,

 

Good info! Thanks!

[Tray]

Thanks everyone for the good info!

 

To recap:

• Most feel the 04 is an improvement from the surging it also gets better MPG and starts easier
  Transmission upgraded
  Some cosmetics were upgraded
  twin spark is more forgiving with regards to TB sync.
  Twin
  I can upgrade a single spark to a dual spark. I will search for that info.

 

 

I may get a single spark that doesn't surge. While I realize this (mine had very little surge but I changed it to a euro spec bike anyway) I think the chance is greater than not that it will have a surge. I'm pretty anal about stuff like that so it would drive me nuts!!

 

Anyone know if the 05's will improve any on the 04's?

[MoDog]

I'd have to agree 100% with RPG...and reaffirm my absolute elation over the lack of surging and the mpg increase of the twin spark '04 RT. I routinely get 48-50mpg while running a steady 80-90mph between tankfuls. On my best tankful to date (and I'll admit to a bit of a tailwind), I filled up in Ft. Collins, Colorado and rode straight through to Gillette, Wyoming (about 300+miles) and I was only about 20 miles into my low fuel light when I pulled into town...and I was rarely under 80mph for the whole time (with an occasional burst at wfo just for the pure joy of it).

[Dan M]

My twin spark runs very smoothly and has no surge at all. I don't have enough time on a single spark to compare power but I did ride an '02 that had more vibration above 4000 rpm. I'm sure state of tune could have been a factor as well.

[Bill Dennes]

My '02 RT has 56k miles now. At 39k I took the heads to San Jose BMW and had the dual spark conversion done. This might make me a good source of comparative info, as I have had both setups on the same bike.

 

I like the twin spark. It improved the rideability of my bike a lot:

 

- Starts easier.

- Power comes on sooner and smoother.

- (Did not eliminate surging altogether. CCP change did.)

- (Did not improve fuel milege particularly.)

 

I won't offer numbers for my fuel mileage because I live in California and I have an Aeroflow windshield. California is good for year 'round riding, and BAD for gasoline quality.

 

I do recommend twin spark.

 

Pack rats will want to dig through their BMW Owners News stack and find the article from about a year ago written by "Dr. Curve." It does a very good job of explaining why twin spark works so well.

[RPG]

Pack rats will want to dig through their BMW Owners News stack and find the article from about a year ago written by "Dr. Curve." It does a very good job of explaining why twin spark works so well.

 

Good of you to bring that up Bill. Read that article as well and really made good sense. Jim Roche also explained that 1100s's with Dual Spark were getting about 2-3 more hp, though BMW was denying any power increase.

 

Also wanted to note how easily my '04 starts compared to my '02. Went for a ride the other day. 28 degrees out. Started as effortlessy and with less protest than my old reliable '96 Chevy pickup (350 Vortec).

 

In addition, I failed to mention to Tray how much smoother the motor is above 4 grand. Noticeable improvements all.

 

Have to stick with my '04. Pics of the new R1200RT have me sort of choking, although I'm sure it's a much improved bike. But enjoying mine too much to really care at this point.

 

RPG

[Tray]

I'll try and find that article. I should have it somewhere!

 

Thanks on the input folks. Smooth seems to be the word of choice for the twin spark! Keep the info coming!

[RPG]

Tray, it's in a previous version of the BMWMOA magazine (summer of last year I think). if you can't locate it, let me know. I copied it and I can fax it to you.

 

Rick

[GaryIF]

I've got an '03 RT that used to surge mildly. It no longer does -- idles smoothly, cold or hot; power curve linear; starts easily. How?

- Precise valve adjustment

- Precise throttle body adjustment

- Techlusion 259 (fuel management firmware that corrects the overly lean fuel mixture)

 

Happy hunting.

Gary

[roadshadowww]

I went from a 02 RT to a 04 RT, big difference in the way these bikes ran across the rpm range, biggest plus was no surging on the 04.

Power was similar but I quickly added a Lazer exhaust with chip and that did make a performance increase.

[Tray]

Thanks for all the replies! I brought my new (to me) 04 RT home today! Rode it about 75 miles. Fantastic!!!

I'm stoked! I plan to ride some tomorrow. Its supposed to be in the low 60's.

[fatbob]

Good for you Tray! You're going to love that bike. I think the twin spark is a big improvement.

[gr8mtn]

Does anyone have any recommended "hot rod" mods for a 2004 rt? I know the 2005 1200 has more power but I don't care for the looks

[Haynes]

Raymond,

I've owned both a single-spark and a twin-spark RT. Had I known that the twin-spark was so different in its delivery of low-down torque, the smoothness of the gearchange and the faultless operation of the rear brake, I would have traded up to the '04 long before I totalled the '01 R1150RT.

[David_Charlton]

I also have an '03 RT,single spark, using Denso Iridium IK22s and it's never surged and runs better after every trip,I can travel at less than 60kph in 6th and no surge I don't think Titanium grey's surge anyway !!!

[Martyn]

My '02 RT has 56k miles now. At 39k I took the heads to San Jose BMW and had the dual spark conversion done. This might make me a good source of comparative info, as I have had both setups on the same bike.

 

I like the twin spark. It improved the rideability of my bike a lot:

 

- Starts easier.

- Power comes on sooner and smoother.

- (Did not eliminate surging altogether. CCP change did.)

- (Did not improve fuel milege particularly.)

 

I know it's not directly cpmparable, but a few years ago I did the same to my old air-head R100RT - noticed same effects as above, except I did get a better mpg - I don't think I'd consider it a deal breaker or a maker, but all else being equal I think the twin spark would be a good bet.

[RPG]

Tray, I had an '02 Single Spark and now have an '04 RT Twin Spark.

 

'04 is much improved over my '02. Much smoother and runs like an old Airhead.

 

No surging like my '02. Transmission is improved and brakes are less sensitive in my opinion.

 

Just rode mine back from my cottage last night. At 75-80mph, I didn't hit the low fuel light until 266 miles, which when I fueled up gave me 46mpg.

 

No complaints here.

 

I LOVE THIS BIKE

[sdpc2]

I have had the same experience as RPG. My '02 was great for the first 1000 miles after a tuneup. After that it surged like a b@#$%&^! Drove me nuts. Then I swapped it out for my '04 twin spark. I too love this bike. Much prefer it over the look of the R12RT. I plan to have this one for a good long time!

 

scott

[thenok]

Ohhh I am looking forward to the quatro spark

[smiller]

Plus, my twin spark will ride on water and then it into wine... the single spark bike could never do that.

[Mike O]

Plus, my twin spark will ride on water and then it into wine... the single spark bike could never do that.

 

I'm satisfied my single spark rides on asphalt (and dirt occasionally) and I enjoy a cold Sam Adams after.

 

Me, I'm waiting for the

 

'no-spark' model,

with dual final drives,

that pulls to the middle,

with air brakes,

and I float above so the damn seat doesn't even need to be there.

 

(hope I didn't leave any major 'anomlies' untouched )

 

Regards,

 

Mike O

[Scurrie]

A little off subject.....for those who have done the San Jose dual spark change, what plugs are you running and are you using the same plug top and bottom?

[Blue Beemer Dude]

The latest iteration of any motor tends to be the best. BMW said the 2-spark was for emissions, but I don't think I've heard anyone complain about surging with a 2-spark.

 

Well then you need to read the board more often.

 

My '04 has a bit of surge. Most of it is gone with a proper valve adjustment and TBS. However, I am an incredibly anal-retentive perfectionist (much to the dismay of my girlfriend) so if it isn't 100% perfect, I'm bitching...

 

So, yes, the twin-spark still has the capability of surging. I've owned two single spark oil heads, and they both surged worse than the twin, so I will agree to say, slightly qualified, that the twin spark will probably surge less than the single spark.

 

But never say never.

 

Michael

[Bill Dennes]

San Jose BMW supplies 2 plugs with the kit (for the new holes) that are a different BMW part number than the stock plug. One plug is Bosch, the other is NGK, and they come out equal in the comparison charts. Go figure. Sorry I don't have those part numbers in front of me.

 

I have run Autolite 3923's in all four holes with no problem.

 

n.b. The San Jose kit provides 14mm lower plug holes instead of the 12mm hole that BMW provides on duial-spark heads.

[AndyS]

I have had both models and can say that the twin spark resolved my experience with surging.

I have noticed NO improvement in fuel consuption (both are good for their size).

I have noticed NO improvement in ultimate performance.

I HAVE noticed greater flexibility in all gears.

I Like the improved horns (twin tone).

The brake balance (SEEMS) better.

I don't like having no choice to switch my lights off.

Overall, the twin spark is the bike I would go for(based on surging and flexibility issues).

AndyS

[jjohnson24]

The law of "Economic Performance Gain"- I spent money on it, yep, I can feel the improved performance- its great! Applies to fuel and oil additives, air filters etc.

[Slartidbartfast]

I had the opportunity to buy and install a GS 5 speed gear box in my RT, and I wish I had done it. I think the lower gearing of the GS would have really worked with the 1100 RT.

Gear ratios are the same (on 1100's at least). I put an RT box in my 95 GS for a while - Part numbers were the same for both models. Maybe FD ratio is different.